If your gut is expanding and your pecs are softening, it's probably because you're not lifting weights. Adults who don't engage in strength training lose five to seven pounds of muscle every decade. Because muscle is active tissue, losing it lowers your metabolism. But 10 minutes a day, three days out of seven, will help. Harvard research shows that just a half-hour of weight training a week does more to reduce your waist size than 30 minutes of brisk walking a day. Personal trainer Brett Hoebel, who's worked with Robert Downey Jr., suggests two exercises. To flatten the stomach, do "V-ups," modified sit-ups in which you lie down and lift your arms, torso, and legs at the same time, forming a V shape. And to firm the chest, Hoebel recommends chest flys. With a weight in each hand, lie on your back on a bench and bring your arms together above your chest. For either exercise, do 4 sets of 8 to 15 reps.

As you age, your skin gets drier and rougher, which causes wrinkles. The changes will be apparent first in the thin skin around your eyes. And sun damage can cause brownish discoloration, age spots, and broken capillaries. What you do about it depends on how friendly you want to get with your dermatologist.

The Products
If you'd rather not see the doctor at all, step up your at-home regimen. In the morning, rub on both a moisturizer with SPF to protect against sun damage and a cream with vitamin C to help rebuild collagen and plump up your skin, which starts to sag as you get older. At night, put on an anti-oxidant cream, like the unscented coffee-berry version made by Revaléskin, which will repair skin cells that have been damaged during the day.

The Treatment
Getting a gentle 20 percent glycolic-acid peel—basically a more effective version of an exfoliating scrub—at the dermatologist's office every couple of months will rejuvenate your skin by sloughing off dead cells, diminishing fine lines and discoloration, and shrinking pore size.

The Injectables
The two most common syringe-based treatments do very different things: Botox is a muscle relaxer that gets rid of lines on the forehead or around the eyes. Fillers, on the other hand, add volume to sagging skin around areas like the jawline and cheeks. Both last about six months, cost $600 to $1,000, and should be performed by a dermatologist, not a plastic surgeon. "Tell them you don't want a lot," says Dr. David Colbert, a New York dermatologist. "You're not trying to change your look; you're trying to maintain it."

To the list of things every guy over 30 should own (a nice garment bag, guest towels) add one more: a pair of eyebrow scissors. Katy Walsh, a brow specialist at Paul Labrecque in New York, says to trim—not pluck—Mike Dukakis–style overgrown hairs. "As you get older, they get coarse and wiry," she says. "Trimming will make a really big difference"—whereas plucking will make you look like a girl. Holding the scissors with the blades horizontal, snip your eyebrows straight across, or, if you're too timid, ask your barber to do it the next time you go for a cut. Cut off any scraggly ear or nose hair, but don't overprune. "There's a reason it's there," says Walsh. The only time you should grab a pair of tweezers is when you spot gray eyebrow hairs. "Tweeze them out," Walsh says. "It won't leave a bald patch."