The squat is a remarkably effective exercise that requires no equipment and can be done anywhere. It targets several major muscle groups and its benefits carry over to many different activities you use in daily life. Getting in and out of chairs and tackling the stairs will be easier on your joints when you build strength and endurance in your hamstrings, quads, and glutes with squats. Plus, by building more lean muscle mass, your body will burn more calories even when you're not exercising, helping to rev your metabolism.  Show us a photo when you’ve knocked this one out.  #idfitnesschallenge

If you have knee issues, stay at the beginner level, making sure your hips stay at or above knee level.  Or, for a more gentle variation, do wall squats with a stability ball behind your back.  It’s always okay to modify!