1. You try to shrink belly fat with crunches

No matter how toned your abs are, your belly won't look flat until you get rid of the layer of fat on top of them. For that, you need to rev your calorie burn. Interval training, in which you alternate high-intensity bursts of activity with easier bouts, has been shown to zap more belly fat than steady-paced moderate workouts. Each week, aim for three interval sessions and two or three moderate, steady-paced workouts of 30 to 60 minutes each—along with ab exercises—for best results.

 

 

 

2. You forget to protect your hands

You wear sunscreen on your face every day, but are you protecting your hands as well? UV protection is the most effective way to prevent new brown spots and mottling, as well as to slow collagen loss. Before going outside, apply a broad-spectrum sunscreen (minimum SPF 30) or sunblock to the tops of the hands and the forearms, areas that get more exposure than palms, advises Deborah Sarnoff, M.D., an associate clinical professor of dermatology at New York University. Reapply generously (a dime-size dab per hand) and often—at least every 30 minutes when active or every two hours when exposed to incidental sunlight.

 

 

3. You’ve gained weight since college

“Next to not smoking, this is probably the most important thing we can do to stay healthy and live longer,” says Walter Willett, M.D., chair of the department of nutrition at the Harvard School of Public Health. Leanness matters for how to look younger, because fat cells produce hormones that raise the risk of type 2 diabetes. They also make substances called cytokines that cause inflammation—stiffening the arteries and the heart and other organs. Carrying excess fat also raises the risk of some cancers. Add it up, and studies show that lean people younger than age 75 halve their chances of premature deathcompared with people who are obese.

 

The government deems a wide range of weights to be healthy (between 110 and 140 pounds for a 5-foot-4 woman), partly because body frames vary tremendously. So to maintain the weight that's right for you, Willett suggests you periodically try to slip into the dress you wore to your high school prom—assuming, of course, that you were a healthy weight at that age. If not, aim for a body mass index of about 23.5.

 

4. You ignore pain

Studies suggest that continuous pain may dampen the immune system—and evidence is clear that it can cause deep depression and push levels of the noxious stress hormone cortisol higher. So enough with the stoicism: Take chronic pain to your doctor and keep complaining until you have a treatment plan that works, says Nathaniel Katz, M.D., a neurologist and pain-management specialist at Tufts University School of Medicine. Your mood will improve—and your immune system may perk up, too.

5. You fight dirty

Nasty arguments between couples increase the risk of clogged arteries. In a recent University of Utah study, women's hearts suffered when they made or heard hostile comments; men's hearts reacted badly to domineering, controlling words. “It's normal to have a fight with your spouse—it's a matter of how you fight,” says Ronald Glaser, Ph.D., an immunologist at Ohio State University. What he and his wife, OSU clinical psychologist Janice Kiecolt-Glaser, PhD., put off-limits: “Getting nasty, sarcastic, or personal, or using body language like rolling your eyes. It's better to simply agree to disagree.”

 

 

6. You forget to laugh

Loma Linda University researcher Lee Berk, DrPH, has tested the effects of what he calls “mirthful laughter” by asking volunteers to spend time doing nothing more complicated than watching TV comedies. He discovered that even anticipating a laugh improves function of immune-enhancing hormones. Berk’s latest study found that over the course of a year, the levels of good HDL cholesterol in volunteers participating in a mirthful-laughter group jumped 26 percent, while their levels of C-reactive proteins, a measure of inflammation linked to both heart disease and diabetes risk, dropped 66 percent. “We call it laughercise,” he explains, “because the benefits of laughter are so much like those of physical activity.”

 

 

7. You don’t volunteer

Pick up trash in the park or shop for a neighbor who needs help, says William Brown, Ph.D., a lecturer of psychology at Brunel University, West London. He studied people in Brooklyn and found that those who had a denser social network and gave more to their friends and family than they received—whether the gift was in the form of money, food, advice or time—reported feeling healthier than others, even when he factored in activity levels. Another study, at the University of Michigan, looked at 423 elderly married couples; after five years, the pairs who were more altruistic were only half as likely to have died. “Many people grow up thinking it's a dog-eat-dog world,” Brown says. “But there's a lot of data that suggests the best way to be healthy is to be kind to others.”

 

 

8. You toss the Sunday crossword

In a University of Alabama study of nearly 3,000 older men and women, those who participated in 10 60- to 75-minute sessions of brain-boosting exercise sharpened their mental abilities so much that their brains performed like those of people more than 10 years younger. Tip: Start small—whip out a booklet of basic puzzles when you're riding to work on the train or waiting in a long checkout line. As your skills improve, graduate to more challenging brainteasers.