It’s been a joke for those nudging up to old age: “If I had known I’d live this long, I would have taken better care of myself.”

But given that the life expectancy of the average American has increased from 74 to 78 in just the last 20 years, it’s no longer funny. People who don’t practice a healthy lifestyle can expect to live longer, but not better.

The Centers for Disease Control and Prevention now says that in just a couple of decades more than a third of Americans will have diabetes, the nation’s number one reason for amputations of lower limbs.

And a study by the Texas-based Cooper Institute and the University of Texas found that people who stay fit with exercise through their midlife years are less likely to develop a chronic disease until the last years of their lives.

Beginning an exercise program today – even a daily 30-minute walk will help – will also benefit the next generation.

People who spend their golden years suffering from a chronic disease turn their children into caretakers, creating an unnecessary emotional and financial burden.

Do everybody a favor: go outside for a walk.