In aging, as with many things in life, it's best to take things one step at a time.

Doctors conclude in the July issue of Harvard Health Letter that one of the best ways to help ensure you'll live past 80 is to first set your sights on making it to 65.

The Harvard Medical School publication also finds that according to various studies, Americans are living significantly longer and healthier lives than just a few years ago. This is good news for the country's aging baby boomers, or "abbies," as the researchers call them.

The raw numbers

But America will have to play catch up if it wants to match the health and life expectancies of some other countries.

The latest figures from the U.S. National Center for Health Statistics state that life expectancy in the United States is 77.6 years. This is a significant improvement from 1990, when life expectancy was 75.4 years, but it's lower than some other countries.

In Japan, for example, the average life expectancy is 80. Compared to the rest of the world, American males and females rank 12th and 15th, respectively, in life expectancy at age 65.

The silver lining

Today, an American man who makes it to 65 can expect to live 81.6 years. Then if he manages to make it to 85, he can expect to live long enough to blow out the candles on his 90th birthday cake.

If a person manages to reach old age, it means they've already beaten the statistical odds and weathered the many dangers that might have killed them but didn't, such as infant mortality, diseases that tend to strike earlier if they are going to strike, violence or deadly car accidents.

As with the rest of the world, American women still outlive men in general, but the gap is closing. On average, a 65-year-old American woman can expect to live to about 85—about three years longer than a man.

Healthier, too

Research shows that Americans are staying healthy longer as well. Disability rates among the elderly are falling, as are mortality rates for afflictions such as heart disease, cancer and strokes. One contributing factor to this trend is that more seniors are living in homes designed for the elderly and which have fewer or no stairs. The availability of medical devices and techniques such as hip replacement and cataract surgery are also helping old people live healthier lives.

Despite these improvements, however, Americans still lag when it comes to years spent in health compared to some other countries. For example, a recent study found that Americans are less healthy than their British counterparts when it comes to cancer, diabetes, high blood pressure, lung disease and stroke. Another recent study found that Americans are more likely than Canadians to have diabetes, high blood pressure and arthritis.

Some of the differences can be explained by differences in screening and testing practices, but other factors are at work, researchers say.

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