Sorry to have to tell you this, baby boomers, but you're not kids anymore.

And even though the 80 million boomers are rewriting the script for aging by staying more active than any earlier generation, they can't stop the clock. Age brings many changes, and boomers must change with it. They have to find a new balance, adjusting the way they live and caring for themselves to make the years ahead happy and healthy.

The secret? Act your age and see your doctor.

"No more sex, drugs and rock 'n roll," jokes David Ruben, M.D., head of the Center for Aging at UCLA. "When people are younger, they can get away with a lot that they can't get away with when they get older."

Baby boomers tend to have a "kind of Peter Pan syndrome," Ruben said. But it's time to face the facts. There's no magic pill or potion or procedure that will keep you forever young. Science isn't going to "cure" aging.

What's next?

You should look at what you are doing-and what you should be doing-to stay healthy. "Psychologically it's hard, but physically it's not hard," Ruben said.

For example: If you're older than 50, have you had your blood pressure checked recently? Have you had blood tests to check your cholesterol levels? Have you gone for a colonoscopy? Nobody likes the thought of having a scope inserted there, but colorectal cancer is a serious post-50 health concern. Unless it's caught early, it can kill.

Have you put on more than a few extra pounds? "There's an epidemic of obesity in the United States," says William Greenough, M.D., professor of geriatric medicine at Johns Hopkins University School of Medicine. When you're younger, you may think you can eat whatever you want. "But as you get into your 50s and 60s, you're going to gain weight...The body can't burn as much fuel, even when active."

Don't worry about high-carb or low-carb food, Greenough said. "Think about the bottom line-calories." And eat healthy foods, like fruits and vegetables.

Get a move on

In addition to changing your diet, make sure you're getting enough exercise. That can just be walking, but whatever it is, you should do it for at least 30 to 60 minutes a day, most days of the week. Walking, or other weight bearing exercise, can help keep bones strong. Shed that flab, get your cholesterol checked and take cholesterol-lowering medicine if your doctor prescribes it. That can cut your risk for heart attack, stroke, diabetes and other debilitating or even deadly diseases.

For health fanatics whose dedicated and devoted exercise has maintained their youthful figures, don't stop. But consider adjusting that exercise regimen.

"Moderation is the key to everything," said Michael Cirigliano, M.D., an internist and associate professor at the University of Pennsylvania School of Medicine. "If you're older and still vigorously active in sports, realize that you're not going to have the stamina you had when you were 24. Take more time to warm up and prepare, and rest more."

Running involves a lot of pounding on the joints: the ankles and knees. Maybe they're starting to get a little achy, maybe a little arthritic. Maybe it's time to think about biking, swimming or yoga. Other physical activities can be just as rigorous and healthy, but less punishing to the body.

If what you're doing is causing aches and pains, Ruben said, "you ought to talk to your doctor about whether it's right for you."

Vision changes, too

And while you may still look great, you may not see great. After 45 you may need reading glasses or progressive lenses to compensate for presbyopia, or difficulty focusing up close, says Richard W. Lindsay, M.D., professor emeritus at the University of Virginia Medical School and a past president of the American Geriatrics Society. You should have an annual dilated eye exam to check for vision problems such as glaucoma and age-related macular degeneration.

One of Lindsay's colleagues at the University of Virginia, Mark E. Williams, M.D., shares his most important advice for baby boomers about getting older. "Stop denying it and get on living with it," he said.

Williams heads the medical school's division of general medicine and geriatric medicine. "I have four secrets to successful aging," he said: "First to challenge your body, second to stimulate your intellect, third to manage your emotions, and fourth to nurture your spirit."

Should you have plastic surgery? Williams asks why. "'I'll have this tucked, that cut out, this changed.' People become caricatures of themselves!"

What baby boomers need, he said, is a whole new way to think about aging. "It's a celebration that we're more, not less."