Keep your chest up, eyes facing forward and arms by your sides.
Stand upright with your back foot on a bench. Lower yourself as close to the floor as you can. Pause, and then push up. Do all reps. Switch legs. Repeat.
Single leg wall squats
Stand with your back against a wall and feet slightly out in front of you to begin. Lift one leg a few inches off the ground (enough to place your weight on the opposite leg). Lower your body into a squat until your weighted knee reaches a 90 degree bend. Hold this position for 10 to 30 seconds. At completion of one rep on one leg, bring your other foot down and switch legs while staying in the squat position. Repeat.