Begin by holding a dumbbell vertically between both hands at chest height. Feet should be just wider than shoulder-width with your toes slightly turned out. Brace your core and keep your chest up. 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 or deeper depending on your range, making sure your knees are pointing in the same direction as your feet and that your lower back doesn't collapse. Inhaling throughout this lowering phase. Pause at the bottom, then extend the knees and hips slightly to perform 1/4 of a rep, before lowering again. Then push through your feet to extend your legs and drive your hips forward to standing and the start position, exhaling as you do so. Do not lock out your knees at the top.