"Service to others is the rent you pay for your room here on Earth," said Muhammad Ali.

When we find ourselves caught up with all the concerns of middle age — aging parents, career issues, children, financial problems, etc. — it's almost impossible to think about adding volunteer work to your overcrowded schedule. But with each passing year, more and more hours open up that give us the opportunity to look around and offer a helping hand to those who need one.

What has just recently become obvious, however, is that being a volunteer literally helps us feel better — about others, ourselves and the world in general. Most people volunteer because it's an obvious way to make a positive difference and help individuals or communities in need. But even if we are inspired by completely altruistic motivations, new research has proved that when we help others, our actions have a boomerang effect and directly benefit us as well. Here are some of the surprising ways that volunteering could help you:

—An end to loneliness: Approximately 46 percent of Americans and 14 percent of people in Britain report feeling lonely. One of the easiest ways to end feelings of isolation is to volunteer to help the aging, the environment, pets, etc.

—Improved job prospects: Volunteering your money, time or skills helps make you a more competitive candidate in the job market.

—Health benefits to enjoy: Most volunteer opportunities involve some sort of active movement, even if it only means getting out of the house. For that reason, volunteers tend to take better care of themselves and live longer. A study on volunteering led by a research fellow at the Harvard School of Public Health reported that "volunteers had 38 percent fewer overnight hospital visits than non-volunteers."

—Increased time: According to Harvard Business Review, volunteering makes you feel as if you have more time. When we spend less time on ourselves (and don't waste time doing things that have no positive impact), we don't feel as "time affluent" as when we volunteer to help others.

—Feeling happier: Researchers at the London School of Economics have found that because volunteering builds empathy, makes us smile and strengthens social bonds, volunteers find a correlation between the amount they contribute and their sense of being loved and feeling happier.

—New friendships created: When you join with others and work toward a common goal, a benefit is better interpersonal connections, closer relationships and more powerful attachments to your colleagues.

—Improved mental health: When people with anger management issues, obsessive-compulsive disorder or post-traumatic stress disorder volunteer to help others, the shared sense of purpose can result in decreased symptoms and improve social function.

—Aging gracefully: Seniors who volunteer benefit the most — emotionally and physically — from giving to others. Volunteering may even lower the risk of heart disease.

—Lower risk of Alzheimer's disease: According to the Journal of Gerontology, helping others can improve elasticity in the brain. This is particularly true for volunteers who are 65 years of age.

Conventional wisdom now holds that people who volunteer over 100 hours a year are among the healthiest individuals in America. Why not start today?

Marilyn Murray Willison has had a varied career as a six-time nonfiction author, columnist, motivational speaker and journalist in both the U.K. and the U.S. She is the author of The Self-Empowered Woman blog and the award-winning memoir "One Woman, Four Decades, Eight Wishes." She can be reached at www.marilynwillison.com. To find out more about Marilyn and read her past columns, please visit the Creators Syndicate webpage at www.creators.com.