This article was originally published on July 13, 2015.Reality check: It’s time to stop thinking of push-ups as a punishment of the drop-and-give-me-20 variety. The truth is, they’re a fantastic strength-building exercise — not just for your arms, but for your entire torso. “Yes, they’re great for strengthening the chest, triceps, and shoulders, but they’re also an incredible core-stability exercise,” says personal trainer Molly Galbraith, CSCS, founder of GirlsGoneStrong.com . “And you’ll even work the glutes as well.”The secret to a good push-up is just that: engaging your whole body and thinking of it like a moving plank (which is basically what it is). It’s also key to send your elbows back on an angle, not winging out to the side, so the chest and shoulders do more of the work. (See our fundamentals guide below for more how-to.)To help you build up the strength toward full push-ups, our 30-day Push-Up Challenge starts you with your hands elevated on a bench (or a couch with the cushions removed). That’s right; you won’t be doing any knee push-ups here — they don’t quite engage the muscles in the same way as having your body in the full plank position.You’ll also be reducing your reps within each successive set to help maintain good form and combat fatigue. You should take at least a minute break between each set, and can even spread the sets out throughout your day if you prefer. Once you’ve mastered the incline push-ups, you’ll take your hands to the ground for a few reps at a time, until you can bang out 10. “The goal is to avoid ‘grinders,’ where you do reps for the sake of the count but at the sacrifice of your form, developing bad habits in the process,” Galbraith says. You’ll also have rest days, which are essential for letting your hard-working muscles recover.