There’s no two ways about it: Working out is virtuous. But if your form is off, you might be doing more harm than good. Here, a few common exercises you’re probably doing wrong...and how to do them right:

Squats Are your knees turning in or splaying out? Keep those babies shoulder-width apart (and in line with your feet) as you shift your weight back into your heels. This reduces stress on your joints and really gets those side thigh muscles burning.

Push-ups We agree: They’re hard. But your hips, back and head need to be aligned to reap the move’s strength and cardiovascular benefits. To test your form, have a friend place a broomstick on your back and make sure it touches your head, back and butt.

Sit-ups You’ve heard not to tug on your poor head while you crunch away, but did you know that just looking at the ceiling can mess with your form and injure your neck? Keep your eyes forward (look between your knees) so your chin grazes your chest as you curl up and over your rib cage.

Want to see how to work out the right way? Check out this easy move that tones your entire body.

More Videos You’ll Love