Fueled by watching TV shows such as The Biggest Loser, a lot of us are obsessed with what we weigh. (Of course, I should talk, since I've got one of those fancy digital scales from Sports Authority that also measures body-fat percentage.) But while poundage is one indicator of health and fitness, it's a sketchy one at best, because it doesn't take into account bone structure and proportion of lean-muscle mass. And the scale can't tell you what's going on inside your arteries after age 40, or what sort of things you're able to do with your body.

While you don't want to throw out your scale or forget about your body mass index, the comparison of weight to height, here are five other numbers that are just as important to watch.

1. Waist Size.

When I checked in this week with North Carolina-based fitness trainer Bobby Morrow, whom I profiled a while back, he wasn't able to talk with me until 10:30 p.m. That's an indication of how many of forty- and fifty-somethings -- the middle-aged exercisers that Morrow specializes in coaching -- are crowding into health clubs, embarking on our perennial New Year's resolution to get in shape. "It's always crazy this time of year," he says, a bit breathlessly.

That we find ourselves making the same fitness resolution year after year, though, should be a hint that there's often something remiss in our approach. Indeed, Morrow says studies have shown that only about 8 percent of the newly resolute who are hoisting dumbbells or trying to figure out how to program the elliptical trainer this week will still be exercising regularly a few months down the road. It could be that their expectations are unduly influenced by TV infomercials, which show preternaturally buff models and promise you can get a six-pack in the time it takes to make three monthly credit card payments.

A few years ago, for martial arts instructor Harry Grimm's 50th birthday, his wife treated him to a trip to Bimini. On a snorkeling cruise, the captain of the boat noticed that Grimm was wearing a T-shirt from a seminar by motivational speaker Tony Robbins (who also, it should be mentioned, is a black belt in the Korean martial art of Taekwondo). As it turned out, the captain had once worked for Robbins as a researcher, and he shared with Grimm an interesting bit of research. When Robbins' organization surveyed middle-aged people about what they most wanted to do before they die, "the number one thing was swimming with dolphins," Grimm says. "The number two thing was getting a black belt."

That insight stayed on Grimm's mind when he went back home to Massachusetts, where he ran a successful Kenpo karate school. It made sense to him. Today, on any suburban strip, you're almost as likely to find a Taekwondo studio as a Starbucks, and Ultimate Fighting Championship competitions are becoming a bigger draw on pay-per-view cable than boxing.

On Thursday, I introduced you to North Carolina personal trainer Bobby Morrow (left), a 63-year-old former U.S. Marine, sheriff's deputy and casino security expert who has found a new calling helping fellow baby boomers remedy nagging health woes through an emerging trend called corrective exercise.

Today, I'd like to share a few of Morrow's best fitness tips, gleaned from my interview with the trainer, as well as his blog and exercise videos on YouTube.

Bobby Morrow has worked at a lot of jobs in his life -- U.S. Marine, sheriff's deputy, studio photographer, blackjack dealer, and head of security at a major Nevada casino, to name a few. But in the past few years, the 63-year-old Lexington, N.C., man has found what may be his true calling: helping other boomers heal their bodies and improve their health.

"People come into the gym and explain that they've got this health problem or this ache or pain, and that it's just old age," Morrow says. "I show them that it's not really their chronological age that's the problem, but poor habits or other things going on that they've probably had since their twenties. But we can do something about that."

Kathy Allin didn't take up golf until she was in her 40s. Now she's found her third career as a golf instructor and likes to help other boomers get into the game.

Allin says she wasn't physically active at all while working in the health insurance industry in Ohio. Then she and her golfer husband, Harry, moved to California for his job, and he bought her a set of clubs and a pink golf bag she hadn't asked for.

Americans are getting older, but some cities are aging faster than others, according to an analysis from The Brookings Institute.

As boomers move to warmer climates, cities such as Scranton, Penn., have seen a decrease in over 65 populations, while others, such as Raleigh, N.C., and Albuquerque, N.M., have seen a marked increase, according to a Huffington Post report on the study.

What was a fad in the 1950s has made a comeback in the modern workout world, with hula hooping classes popping up everywhere. According to the American Council on Exercise, hula hooping burns an average of 420 calories an hour and is a low-impact cardio workout that's easy on the joints, improving coordination and tightening the core.

"The weight loss and cardio conditioning attributes are attractive to new students, and the mind-body benefits keep them engaged," says Gabriella Redding, CEO of Hoopnotica, a Los Angeles-based hoop dance company.

Retirement communities are an American tradition that dates back at least to 1922, when the Loyal Order of Moose opened Florida's Moosehaven, aka "the City of Contentment," which in its initial form bore less resemblance to Leisure World than it did to an Israeli kibbutz. Fraternal retirees and their spouses helped subsidize their upkeep by working on the community's dairy farm. Even if milking cows isn't your thing, you have to admit that Moosehaven's founders were gerontological visionaries. They imagined older people not as bored couch potatoes but as vigorous and energetic folks who enjoyed the sense of accomplishment and reveled in physical activity as a way to stay youthful.

I was reminded of Moosehaven when I read recently about BOOM, a proposed California retirement community near Palm Springs that is scheduled to break ground in 2012, and which recently has been getting a lot of attention in architecture publications and at the Huffington Post and the Los Angeles Times. The project was spawned when a client showed a 40-acre site to Matthias Hollwich, the co-founder of New York-based architectural firm HWKN, who's been investigating how architectural design could be used to optimize older people's lives. Originally, BOOM was envisioned as a magnet for urbane, design-conscious gay and lesbian retirees, but along the way, the concept has expanded to appeal to anybody who craves the chance to get away from polyhedrons of any sort whenever possible.

Tim Dale once owned more than a half-dozen restaurants and nightclubs in San Francisco. But a sabbatical from the business world took his career in a different direction.

He started practicing yoga during his three-year break from the nightclub scene. Dale, who had always been active in cycling, skiing and rock climbing, decided he needed a change in his fitness routine. "My body was asking for it," he says. "I think it got a little beaten up from all the high-impact sports."