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Companies that do good tend to do well. As we search for the world's greatest companies and leaders, we focus not only on each business itself, but also on how that company contributes to a better world.

Take Whole Foods Market (Nasdaq: WFM). One of its core values is caring about our communities and our environment through efforts such as sustainable agriculture and community citizenship. Whole Foods gives a minimum of 5% of profits every year to good causes. And it's no secret that Berkshire Hathaway's (NYSE: BRK-B) own Warren Buffett and Charlie Munger put charitable giving at the top of their list. Munger gave $2.4 million in Berkshire stock to charities late last year, and Buffett has pledged most of his wealth to the Bill & Melinda Gates Foundation.

Our leader here at The Motley Fool, CEO and co-founder Tom Gardner, recently interviewed Louis Zamperini. Recognized as an American hero, Zamperini was a World War II prisoner of war and is the subject of Laura Hillenbrand's new book, Unbroken. In this part of the interview, Zamperini talks more about doing good and forgiveness. The following is a lightly edited version of their conversation:

Tom Gardner: How do you advise someone who feels faithless to find their faith?

Louis Zamperini: Well, my family has never seen me mad. I just don't get mad because the Bible says, "Return good for evil." I am confronted with anxiety, but I don't let the anxieties in, and so I can honestly say that I have always had a cheerful attitude.

We believe as Christians that all things work together for good. For instance, I broke my hip about three years ago. I thought I shattered every bone in my body. I am lying there on the pavement, it's dark, the neighbors aren't home, and I am alone. I have got two flights of stairs to go up and four rooms to drag my fanny through, and I just looked and I said, "God, I know all things work together for good. This had better be good."  (Laughs.)

When I went to the hospital, listen, it was worth it. I had so much fun and everybody in the hospital came in to see me because they said, "God, you are so cheerful and you have got a broken hip." I said "Well, I have had worse things than that. " I made a lot of friends and all the nurses went out, nine of them, and bought my book. So it was worth it.

It shows no matter what happens to you, if you accept it cheerfully, you will have a great attitude and you will heal quicker because when you are cheerful or doing good, you get a flood of white corpuscles in your immune system. That controls the body. When you get a powerful immune system, you heal quicker and you don't get sick.

Gardner: A lot of us like to see the forces of evil defeated, and we like to see the bad guys suffer. When we read your book and your life story, Mutsuhiro Watanabe is obviously such a dark force. Yet your perspective on him has transformed through your life, and I just would like to hear you speak a little bit about that, so that those of us who face something dark in our lives might actually take a different perspective on it.

Zamperini: When I came home, I was so filled with rage over the Bird [Watanabe], after what he did to me over a couple of years. I was trying to make money so I could go back there, secretly seek him out and do him in. I really wanted to do that, so I had probably the worst case of vendetta that you ever heard of, and yet after receiving Christ, it was just the opposite. I wanted to go back and give the guy a hug and tell him I forgave him.

I did go back, and went into Sagamo Prison, and I looked for [Watanabe], and he wasn't there. They said he had committed harikari, so I assumed he was dead until CBS found him just before the Nagano Winter Olympics, and then he sent me over there twice to do a video, not only carrying the torch alongside my former slave labor camp, but to meet the Bird. Then they started to do a 60 Minutes on him, and they accused him of all these crimes. His son and grandson were standing there, and boy, they didn't like it. They didn't know he had committed those crimes and they said, "No more of this." They could never get back to him again. They did a video that won an Emmy award. The only footage ever taken of Watanabe is in that video.

Gardner: What are a few things that you want to achieve now, and add to the list of 84 forms of mastery that you have gathered up in your life? What accomplishments are you pursuing now?

Zamperini: Well, I gave up skateboarding on my 81st birthday, and I gave up skiing on my 91st, but I am so active now speaking. I am a motivational speaker and I speak at universities. I just spoke at USC last week to 300 athletes. And I lecture aboard cruise liners. The idea is to motivate people to work hard for their corporation and not as if they are giving away their life, because when you work hard and appreciate your work, you are getting the benefit of the white corpuscles flooding your immune system. You just don't get sick. And when you are working hard for your company, you keep them solvent. It is a good idea for people to have both things on their mind. You do good for your own benefit and you work good for your company. So you both benefit from it.

When you do good, you feel good, right? If you feed a guy on the street or buy somebody a meal that is a homeless person, you feel good. That feeling is your immune system being flooded with white corpuscles, so that is the secret of longevity. That is a secret of my life. People say, Well how can you have such a great memory at your age?  Well, that is one thing that helps. The other thing is memorizing. I memorized great passages from the scriptures and all those things I think would be pertinent in my work with young people. Memorizing keeps you from going senile and becoming a scatterbrain.

Gardner: Have you read Unbroken? I assume you have; what do you think of the book overall?

Zamperini: Well, the book I wrote is called Devil at My Heels. When I wrote it, it reminded me of being in prison camp. But when I read Laura's book, it put me back in prison camp, it is that graphic. I could only read a chapter a day, and I had to look out my window here over at L.A. to be sure I wasn't back in prison. Everybody who writes me a letter, they say the same thing: "Now I know how you guys suffered in prison because I was with you in the book." The way she describes stuff, she, too, was suffering for 23 years, much more than we suffered in prison, so she can relate to our suffering and you see that in the book, as the woman is a genius writer.

The fact is, she did this while severely ill. There were six months in which she couldn't write or talk. Then she finally called me and said, "Now I can talk and I can write." Right now, she is bedridden again. People call me and tell me I am their inspiration. Well, she is my inspiration. I don't know how she can handle it. She is a real inspiration.

Gardner: And an absolutely brilliant writer and thinker.

Zamperini: Alongside that, yeah; just a fantastic woman. Sweet as can be. I didn't know she was there.  I was doing the book with her, and then I read in the paper about her illness. She doesn't talk about her illness. For six months, she couldn't write or talk. Then she started back on the book again, and then she had another three or four months in which she couldn't write or talk, and then back on the book. That is why the book took seven years. Her research is endless. She won't print anything unless she finds the truth out for herself.

Gardner: It comes across in every line in the book. It is such a wonderful book and obviously such a remarkable story that inspires.

Stay tuned for the fifth and final part of our interview on Friday.

Motley Fool CEO and co-founder Tom Gardner owns no shares of any companies mentioned. Stock Advisor analyst Jason Moser owns shares of Berkshire Hathaway. The Motley Fool owns shares of Whole Foods Market and Berkshire Hathaway. Motley Fool newsletter services have recommended buying shares of Berkshire Hathaway and Whole Foods Market. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.