Life changes when you retire. Aside from the loss of earned income, many other things change as well. You lose the structure that work brings to your day, the companionship of your coworkers, and the sense of purpose that comes from working through your tasks, projects, and other challenges.

Despite all those changes, if you plan it well, retirement can be an incredibly satisfying time of life. But if you have no retirement plan, you may find yourself wishing you were back at your job -- even if you didn't particularly like that job while you were doing it. Key to a successful retirement is managing your money and your priorities well so that you can make the best use of the time, money, and health you have available to you.

Fill the gaps that leaving work creates
The time you get back when you retire can be a blessing or a curse, depending on how well you fill it. According to a survey from Bankers Life, the top two things retirees miss about work, aside from the income, are interaction with their coworkers and the fulfillment that comes with the job. Finding outlets to fill those two gaps can go a long way toward ensuring you have a happy retirement.

Volunteering can help a great deal on both fronts. It gives you more structured days, a sense of accomplishment, and interaction with like-minded people and the community you serve. Not only can it help fill your days with satisfaction, but it could even prolong your life! A 2013 research review published in BMC Public Health suggests that people who volunteer have a 22% reduced chance of early mortality compared to people who don't volunteer.

If volunteering is not your style, then exercise is another great way to maintain your mind, mood, and health. While we all may slow down a bit as we age, exercise has been shown to slow the onset of many age-related illnesses. And even here, you can get creative. If hitting the gym isn't your style, perhaps offer to help watch your grandkids to cut your own children's child care costs. Chasing your grandchildren around can be a great way to keep you moving. In addition to the exercise, it can provide some great quality time with your family.

No matter how you fill your retirement days, they're still 24 hours long. Your challenge in retirement is to find ways to fill those hours in ways that are meaningful to you while still allowing you to support yourself on the money that is coming in.

Get creative with your cash
Speaking of money, the typical retiree currently receives about $1,328 from Social Security each month. That's about 36% above the poverty threshold for a single person -- enough for a spare lifestyle in a low-cost part of the country, but not much more. Your savings and any pension you may be eligible to receive must bridge the gap between what Social Security provides and what you need to live a long, happy retirement.

If money's tight, think of low-cost ways to do what you enjoy most. For instance, consider volunteering at the local symphony or theater, which usually gets you into the show for free. Giving your time to something you love can combine saving money, making a difference, exercising, and having fun. Talk about the foundation of a fulfilling retirement!

Make your retirement the best career you'll ever have
Your retirement may well last decades. Social Security's actuarial tables indicate that an average 60-year-old man can expect to live another 21.3 years, while an average 60-year-old woman can expect to live another 24.3 years. You may well live longer, particularly if you stay active and healthy. That's a long time -- almost an entire second career.

The time you get back when you retire gives you an incredible opportunity to fill your days with the things that matter to you the most. Focus on your health, your family, and your community while managing your resources well, and you just might discover that your retirement is the best career you've ever had.