I recently started doing 100 pushups a day. I don't have a lot of time to exercise and frankly, it's the least time-intensive way to fend off the batwings flying swiftly toward my middle-aged self. But it turns out having more muscle mass affords a host of ancillary benefits that can radically improve anyone's life.

Protection from Stress

Strong muscles help your body purge a harmful protein associated with stress-induced depression. That's according to a recent study conducted on mice at the Karolinska Institutet in Stockholm, which found that conditioned muscles adapted to exercise express enzymes that detoxify a substance called kynurenine, a byproduct of stress and inflammation.

Slow the Aging Process

In a refreshingly optimistic article on aging, Prevention's Ginny Graves recently described how metabolically active muscle--the kind that's lean and packed full of the metabolism-boosting mitochondria within your cells--affects everything from your weight to your energy to your risk of becoming sick. Sit around in front of a computer all day, shun the gym and watch TV every night and the number of mitochondria in your muscles drops. The good news: You can increase your mitochondria via aerobic activity. "As your muscles demand energy, the mitos themselves, along with enzymes in the tissue, switch on genes that start transcribing mitochondrial DNA," she writes. "The more you stick with it, the more you make, and the more efficient your muscles become at burning fat and providing energy."

Higher Metabolism

Older people--even if they eat and workout the same amount as younger people--burn fewer calories. Staying active and maintaining your muscle mass slows this slowdown, however. "Muscle is active tissue, and similar to the way an eight-cylinder car burns more gas at idle than a four-cylinder car, having more muscle mass burns additional calories even when you are at rest," writes Dr. Ed Blonz for the San Jose Mercury News. And of course, a higher metabolism means you'll carry around less weight.

Better Posture

Sitting and standing with good posture makes you look more confident, and everyone knows confident people are more successful than their diffident counterparts. Strengthening your core muscles--which include abs, back and hips--helps stabilize your spine and keep it aligned. According to Canyon Ranch, which is known for its health-focused spa resorts, a weak core can lead to not only slouching but a slew of health problems such as neck and shoulder tension, lower back pain, digestion and breathing problems, as well as fatigue and headaches.

More Opportunities

Strong, toned people are more attractive and like it or not society rewards better-looking people with more opportunities. Just take it from Dustin Hoffman, who had an epiphany after seeing himself on the screen made to look like a woman for the movie Tootsie. The actor says he asked makeup artists to make his female character look better, to which they responded that they had done the best they could with his face. "I think I'm an interesting woman when I look at myself on screen and I know that if I met myself at a party I would never talk to that character because she doesn't fulfill physically the demands we're brought up to think women have to have in order for us to ask them out... There's too many interesting women I have... not had the experience to know in this life because I have been brainwashed," he said tearfully in a YouTube video that has garnered more than 5.5 million views. "And that was never a comedy for me."

No Gym Required

Too many people think putting on muscle means living at the gym, which isn't true. Just find a few favorite moves you can squeeze into your day, such as pushups for your arms, the plank position for your core and squats for your legs and butt. And no, you're not too busy. Even when he's stressed out with a full calendar, speaker, consultant, author and frequent traveler Peter Shankman takes a few minutes to bump out three sets of 20 pushups spread out over an hour. "At the end of the day, it has to come down to balance," Shankman says. "If you want something enough, you'll work at it."