If you are a “baby boomer” or older, you may remember walking to school and a school period called recess. Your parents may have also walked to work, and you probably rode your bike to the store to help run errands.

You may even remember a quirky guy on TV named Jack LaLanne, who was encouraging us to exercise regularly and keep moving. Well, Mr. LaLanne, also known best as one of the earliest American fitness gurus, died in January 2010 at the age of 96. Many attribute this longevity to his vigorous exercise program and subsequent level of fitness.

Things have changed since the early 1950s, and, in general, America is now noticeably underexercised and less fit. Therefore, I encourage you to determine your own definition of physical fitness.

It will not be the same for everyone, but one of the best definitions, in my opinion, can be found in the October 2002 Crossfit Journal. You can look this up on the Internet and be sure to read its reference to “World Class Fitness in 100 Words.” It uses the words “endurance, stamina, strength, flexibility, power, coordination, agility, balance and accuracy” in its definition.

It has been shown that lack of regular exercise is associated with obesity, diabetes, heart disease, osteoporosis and even cancer.

It has also been shown that “regular lifelong exercise reduces mortality in humans” but may not extend “maximum life span.” However some studies believe that regular, lifelong exercise may help add one or two years to your life.

Exercise may help reduce premature aging by helping to prevent osteoporosis, diabetes, heart disease and other diseases, so why not “add life to your years” by improving your quality of life through physical fitness?

By the way, it also helps to choose your parents wisely. Jack’s brother Norman lived to be 97, and Norman was not a physical fitness addict.

David Keisler is a gastroenterologist and internist in Aiken.