Secure your feet under the foot pads of the machine and ensure the calf pad height is set so the top hits below the knee joint. Cross your arms over your chest and bending at the knees, drive your hips back and down as if you are going to sit on a chair. Lower slowly with control until your thighs are parallel to the floor and that your lower back doesn't collapse. Inhale throughout this lowering phase. Pause at the bottom, then push through your feet to extend your legs and drive your hips forward to return to the start position, exhaling as you do so. Do not lock out your knees at the top. Repeat.