The author at the finish line two days before the 2013 Boston Marathon.

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Two hours, fifty-five minutes, and forty-seven seconds after excitedly striding over the starting-line timing mat, I crossed the finish line of the 2013 Boston Marathon. It was a personal record. I turned and gave Adam a hug. I had just met Adam two hours and fifty four minutes earlier and he proceeded to coach me to my best-ever marathon time.

It had all the trappings of a truly memorable athletic event: goals achieved, heartfelt camaraderie, wildly cheering fans (even if I didn't stop to kiss any of the beckoning Wellesley girls), and, of course, all of the hoopla of one of the biggest races in the world. The weather was perfect, and the 27,000-runner race was beautifully organized. I was beaming and, after picking up my drop bag, began fielding an influx of congratulatory messages from family and friends.

Adam and I limped our way through the buffet of post-marathon food, smiling, recounting the race, and making plans to meet for future races. We stuffed our faces with Hawaiian rolls and granola while guzzling Gatorade.

I gave Adam a parting fist bump and headed to meet another friend -- Seth Jayson, a sharp-witted, wise-cracking fellow Fool and avid marathoner. Normally flanked by a cheer section of his wife and daughter, he was flying solo for this race. And because he'd scheduled his flight back soon after the race, he'd had to check out of his hotel in the morning, before the race. As a favor to whomever he'd be sitting next to on that flight, I'd offered to let him shower in our hotel -- the Lenox, located just across the street from the finish line.

My mom was running the race with the Girl Scout charity team and I needed to get back out to meet her at the finish line. I still had time though -- I was tracking her online and I calculated that it'd be around 20 minutes before she'd be finishing. Nevertheless, it'd be better to get out there sooner. I didn't want to chance missing her finish, and we could cheer on other runners in the meantime.

When Seth and I arrived back at the hotel, the Boston Marathon gear-clad employees and a gaggle of random guests gave us a round of applause. I was more than a little embarrassed. I awkwardly nodded and we hopped on the elevator. Seth and I reviewed our respective races. He showered. He dawdled and, in his good-natured way, poked fun at himself for it. I continued to watch the updates on my mom. She had tweaked her back and was worried that she'd run slower than usual. She was. Finally, Seth and I gathered our stuff and prepared to head to the finish line to cheer on my mom. "Hang on," I said, "I'm going to use the bathroom." I was taught young by my doctor aunt to never ignore my bowels. I had no idea how fortunate the advice would prove that day.

I hustled out of the bathroom, stuffed $10 in my pocket and grabbed my half-eaten bag of Hawaiian rolls. I was standing by the window.

Suddenly, I heard what sounded like a cannon blast. I looked out the window and saw a plume of smoke. People were running, I saw good Samaritans dragging flailing, injured bodies out of the blast zone, police knocked over barricades. "Jesus," I gasped, "was that a bomb?" Seth was sure it was. We froze. Seconds later another blast sounded. We could hear screams from the streets below.

My first thought: I was safe, but my mom was still out there. I picked up my phone and called my dad. In an unusual turn, neither he nor my wife had come to the race to cheer us on for this momentous race. "Dad, I think there was just a bomb at the finish line. I'm OK, and I'm going to find mom." I hung up. I tried to call my wife, but the line had gone dead. I texted "I think a bomb went off at the finish. I'm safe and as far as I know mom is too I'm going to look for her." Hawaiian rolls still in hand, Seth and I rushed to the lobby.

The room seemed strangely still. Employees didn't seem panicked, but also didn't seem to know what to do. You could hear screams and sirens from out on the street. We squirted by a crowd of people at the front door and tried to figure out where we could go. Streets were blocked by uniformed officers or fully barricaded. The last checkpoint my mom had registered was 40 kilometers, which meant that she was, at most, a mile from the finish -- I prayed she was at least that far away.

A volunteer we passed offered that runners on the course were being diverted to Boston Commons. In the best of times my navigational skills are barely north of awful. Now I was also in a fog. Seth pulled out his phone and suggested we make a wide loop to avoid the blocked off streets. I just followed him. We walked together for a few blocks. He pointed out Boston Commons and said he was going to hoof it to Logan Airport to try to catch his plane. As with my wife and family, it was unusual that his wife and daughter had skipped the trip to Boston. He was obviously shaken by what could have been.

I fielded texts from friends and family expressing concern. I sent texts assuring people that my mom would be OK -- I just had to find her. I was partially feigning confidence -- the mobile tracking systems at races are often inaccurate.

When I finally reached Boston Commons there was hardly anyone there. It didn't look like runners had been directed there after all. I spotted another volunteer and asked him for information. "I think they're being sent over to Stuart. But it's awful over there -- people are dead, other people lost limbs. I don't know if you'll be able to get over there."

"I have to," I replied, "my mom is still out there." The volunteer patted me on the shoulder and wished me luck.

The family meet-up area was on Stuart Street and the day before, my mom and I had agreed to meet there in case I didn't see her at the finish. I positioned myself under the "K" sign. Runners filtered in, and there were tearful embraces with loved ones. Police and military dashed by. Sirens blared. Bomb-sniffing dogs barked.

I texted my mom to let her know exactly where I was. If she somehow got access to her drop bag, she'd have her phone. I paced. Up to "A," back down to "K." I peered down the police-guarded rows of buses that held one batch of drop bags. I called my mom and left her a message as I shuffled back to "K." I watched vacant-eyed runners wander by.

My phone buzzed constantly with well-wishing text messages. At one point, I looked down and my heart leapt when I saw my mom's name in my missed call list. I dialed back and then texted before realizing it was just the outbound call I'd placed to her. Thinking she may have headed to the hotel, I texted her to say we should meet there.

I set off running. My legs burned, but I was sick of waiting. I took a wide loop back toward the Lenox. I walked. I ran some more. I could see the hotel. I limped up to an officer standing in front of yellow caution tape.

"Where are you going?"

"That's my hotel."

"It's closed, it's been evacuated. There's no way you're getting anywhere near there."

I hobbled back out to the intersection just as my phone buzzed. It was my wife. My brother had heard from my mom. He said she'd borrowed somebody's cell phone and texted to let him know that she was OK. She was headed to the hotel.

I sunk down on a sidewalk planter. Everything wasn't OK. But for that moment, knowing that my family was safe, I felt better. I looked down and realized I was still tightly grasping the bag of Hawaiian rolls. I absent-mindedly began to eat.

A reporter with cameraman in tow headed in my direction. She asked if I ran the race and if I'd mind taking to her. I didn't mind. I told her what I saw from the window. I said I was concerned about my mom but was relieved when I'd heard that she was OK. She asked if I had any takeaways from what happened. I said I didn't know much about what happened, so it was a little early for that.

"Are you angry?" She asked.

"Angry?" I had no idea. I was confused. "No. I'm not. I'm... no I'm not angry." She ended the interview.

I asked what they'd seen. They were right there. They'd seen blood. Lots of blood. Limbs hanging off. People terrified. I said I was sorry -- the physical injuries are awful, but it's got to be scarring to have to witness that kind of carnage. They thanked me and left.

The author and his mother before the 2013 Boston Marathon.

My phone lit up. It was my mom and she'd managed to get her cell phone. She texted that she was on her way to the hotel and I told her there's no way we'd get in. We wearily navigated toward each other and finally met up. I was too tired to be emotional, but I was emotional anyway. We both cried.

The hours that followed are a bit of a blur. We wandered around. We found a woman shivering, alone on a street corner. She said she had a rare disease and her muscles and lungs were starting to seize up from the cold. She implored us to not get medical help -- she had a ride coming and the EMTs wouldn't know how to respond to her disease. So we got her blankets and waited with her. Eventually, her ride arrived.

We started to get cold and found a burrito shop. I had $10 in my pocket, but the kid behind the counter said he'd charge us for a couple of coffees and give us a large burrito along with it. Chalk one up for the much-maligned younger generation.

I continued to field a humbling torrent of concerned texts and Facebook posts. I began to feel guilty -- don't worry about me, I'm fine. There are people that are dead. There are people that will never walk again. Yet, physically tired, emotionally wrung out, still clad in my race clothes, and smelling really, really bad... I appreciated it all.

We made our way back to the hotel eventually, but it was still locked down. The manager at a nearby Marriott welcomed us and allowed us to stay warm in the lobby. He brought us sandwiches and lent us cell phone chargers so we could continue letting family know we were OK.

Around 9 p.m., we were able to walk through the parking lot of police and military vehicles and two officers accompanied us to our room in the Lenox to retrieve our belongings. We packed quickly and nervously chatted with the officers. One was visibly angry -- I thought he'd start spitting as he talked. He couldn't imagine what kind of animal would do such a thing. The other officer was a born-and-bred Bostonian. There was more optimism in his voice. Boston would pull together. They'd show their true colors, and next year, the race would be a testament to that.

We were ushered back out of the Lenox just as quickly as we'd gone in. We booked a room at the Marriott and schlepped our bags up to our new, 10th-floor room. I went back out into the cold night, back past the police checkpoints, past the barking from the SUVs emblazoned with "K-9 unit," past the hazmat trucks, the hordes of jabbering media, and the screaming sirens.

I ordered two pizzas inside the oddly bustling Salty Pig. The boisterous crowd felt jarring, so I left and waited outside.

As I sat waiting, I thought back to the newswoman who had interviewed me. Was I angry yet? I waited. And waited. I wasn't. Whoever did this was angry. I was just sad. I was sad that the families who had come out to cheer and support loved ones had been gravely injured, and killed. I was sad that we live in a world where not only does this happen, but it happens all the time. I was sad that even though the newscasters kept telling me that this was an "unimaginable" event that it wasn't unimaginable at all.

I did, however, realize that there was a takeaway after all. I realized that had my mom run a little faster, had Seth taken a faster shower, or had I decided to skip one last trip to the bathroom, the three of us may have all been right at the finish line as the bombs went off. Had my uncle not had to leave early for a meeting, he and my aunt would have been there. Had my wife, my dad, my brother, sister, or any of my other family members been at the race -- as they almost always are -- they would have been right there, smiling, cheering, and at risk.

So often, life seems so big. We get married, have kids, save for retirement. We make big, important decisions. We worry about whether we said the wrong thing during a meeting or if we bought the right smartphone.

Then, every so often, we're reminded just how much can come down to a matter of mere minutes, or even seconds, in one direction or another. I don't know that I'm smart enough or wise enough to know what that "means," but I do know that it puts a lot in perspective awfully quickly.

I picked up my cell phone and dialed my wife. Before she said anything I told her I loved her.

I scrawled this out from Logan Airport on my tablet, and then my cell phone when that died. I hadn't been to Boston since I was knee high, but I'll be back. I'll be back to run the Boston Marathon. Not because I think this was "unimaginable," or that it can't happen again. I'll be back because the person that did this wants the opposite reaction. And I'll be back because when I see life coming down to small, seemingly random decisions and increments of time, it doesn't inspire me to not live. It inspires me to live that much more -- to make sure those that I love know it, to seize opportunity, and to make it perfectly clear that hate, anger, and violence don't win.