Grip a pair of dumbbells firmly in both hands and stand with your feet slightly wider than shoulder width. With a slight bend in your knee, slowly hinge your hips back, inhaling as you do so and keeping a neutral spine. Keep your arms extended and the dumbbells close to your thighs throughout the movement. When your hips have hinged as much as possible, proceed to reverse the movement. Drive your hips forward with force, squeezing your glutes and hamstrings as you do so and exhaling. Pause for a count of one at the top, keeping your glutes tensed. Then begin the second portion of the movement: 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, making sure your knees are pointing in the same direction as your feet 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.