However, vanity as much as wellness may be a driving force--and the search for six-pack abs does not end after one's 50th birthday.

At least 63 percent of seniors are more concerned with their abs than any other part of their body. Only 10 percent are concerned about their hips or bottom, and only 5 percent are worried about their legs.

The survey was commissioned by health benefits company Humana Inc. (NYSE: HUM) and the SilverSneakers® Fitness Program, a product of Healthways, and was conducted on eons.com, the Web site of Eons, Inc., a 50-plus media company.

The survey also revealed that 74 percent of seniors exercise at least three days a week and 33 percent exercise at least five days a week. Nearly half (46 percent) have been exercising for more than five years, demonstrating a long-term commitment to physical activity.

Of those surveyed, half prefer to walk or power walk to get their exercise, and, if given free time to do any physical activity, 39 percent say they'd take a long walk. Nearly half (47 percent) like to exercise outdoors, while 40 percent prefer working out at home and 43 percent like to exercise alone.

Other key findings of the survey include:

• 17 percent say they've lost weight since becoming more active; 34 percent say their body just feels better.
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• 53 percent say that a lack of interest, motivation or time prevents them from being more active.
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• 61 percent say they started exercising because they wanted to look or feel good.
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• Only about 15 percent said it was because of a doctor's warning (5 percent) or an immediate health concern (9 percent)Less than 1 percent said it was because they were re-entering the dating scene.
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• 67 percent exercise today to improve their health or maintain their fitness/health level.
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• 44 percent say their personal belief is what keeps them going.
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• Only 7 percent say it was their children (<3 percent), doctor (<3 percent) or a friend (2 percent) that motivated them.
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• 22 percent say they'd take an adventure vacation, go kayaking or canoeing if given free time to do something physically active.

To help inactive seniors jump-start their fitness, Humana developed a fitness book with low-impact exercises and tips on getting and staying healthy.