If your goal is to get jacked, resist the urge to only focus on your vanity muscles. Though it may seem like hitting the gym every night and performing a bunch of bicep curls and tricep press-downs will help build the buff bod you're yearning for, by following this approach you're actually doing yourself a disservice.

Aside from the fact that an imbalanced physique is at greater risk of injury, focusing only on these smaller muscle groups deprives your body of its full release of testosterone. Because such a large percentage (60 percent) of your overall muscle can be found in your legs and back, working these areas will actually benefit your whole body. And, when you tax these larger muscle groups, your body releases greater amounts of natural growth hormone, causing you to grow all over.

So, the next time you're at the gym, rather than hammering out your umpteenth set of dumbbell curls, try performing some sets of deadlifts and squats. Your body -- even your vanity muscles -- will thank you with the muscle growth you've been hoping for.