Baby boomers are living longer lives than their predecessors, but not necessarily healthier lives, according to a new study that warns of rising health care costs.

Men and women born between 1946 and 1964 were more likely to suffer from high blood pressure, high cholesterol and diabetes than the generation before them, according to the study, published today in JAMA Internal Medicine. They were also more likely to be obese and less likely to exercise.

"Despite their longer life expectancy over previous generations, U.S. baby boomers have higher rates of chronic disease, more disability, and lower self-rated health than members of the previous generation at the same age," the study authors wrote. "On a positive note, baby boomers are less likely to smoke cigarettes and experience lower rates of emphysema and [heart attacks] than the previous generation."

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The study supports a gloomy forecast for healthcare costs as the oldest baby boomers approach their 70s. Americans spend roughly $147 billion on obesity and $177 billion on diabetes, according to the U.S. Centers for Disease Control and Prevention.

"We've got a mixed report card here," said Dr. William Schaffner, chair of preventive medicine at Vanderbilt University Medical Center in Nashville, Tenn. "We've got some As and Bs, but certainly some Cs and Ds with pretty serious implications for medical care in this country."

But Schaffner say it's never too late to turn things around.

"Exercise and diet continue to be very important as we get older, and it's never too late to quit smoking," said Schaffner, adding that exercise doesn't mean "training for the Olympics." "There are lots of easy things people can do: walking, swimming, gardening - physical activity of any kind."

ABC News' chief health and medical editor, Dr. Richard Besser, said the study should serve as inspiration for baby boomers with a lot more living to do.

"You can start to make a difference in your risk for all of these by making small changes in what you eat and how you move," he said. "It may not be easy, but it's very simple: Start small, achieve success, and build from there."