Doing a swan dive from the 10-foot dive board, he comments that no other 90-year-olds are well enough to join him. Indeed, it's rare sight to see a 90-year-old doing any kind of physical activity these days.

That doesn't mean you have to grow decrepit with age, however. You too can enjoy physical activity well into your senior years. The key, of course, is to stay active. The good news is, it's never too late to start. My mother started a strength training program at the age of 74 after recuperating from a nasty fall, and was able to make significant gains within a couple of years.

So, if you're ready to take control of your health, keep reading. Below, I list five key focus areas to help you stay fit after 50. Exercise may be particularly important for women entering menopause, as this is when changes in hormones begin to weaken their bones.