The push-up is the most useful bodyweight exercise there is, and also the most commonly butchered. Fixing your form takes five minutes and instantly makes the move more effective and easier on your shoulders.

Set up the plank Start in a high plank with hands slightly wider than your shoulders, fingers spread. Your body should form one straight line from head to heels. The two most common faults appear right here: sagging hips and a hiked-up rear. Squeeze your glutes and brace your core to lock that line in place.

The descent Lower yourself by bending your elbows, keeping them at roughly a 45-degree angle to your body, not flared straight out to the sides. Flared elbows are the leading cause of push-up shoulder pain. Lower until your chest is about a fist's height from the floor.

The push Drive back up by pushing the floor away, keeping that straight body line the entire time. Do not let your hips rise first; the whole body moves as one unit.

Common fixes - Hips sagging? Brace your abs harder, as if bracing for a punch. - Cannot do a full rep? Elevate your hands on a couch or counter. This is a real push-up, just scaled. - Neck craning? Keep your gaze on the floor a few inches ahead of your hands.

The payoff A properly performed push-up trains your chest, shoulders, triceps, and core all at once. Quality over quantity always wins here: five clean reps build more than fifteen sloppy ones, and they protect your shoulders in the process.