Set up a squat rack station so that a barebell is at knee height when resting on the rack. Do this either by lowering the safety bars or by standing atop an aerobic step or solid platform. Stand with your feet shoulder width apart. With a slight bend in your knee, slowly hinge your hips back, inhaling as you do so and keeping a neutral spine. Grip the barbell firmly in both hands, with an overhand or mixed grip depending on your preference. Shoulders should stay back and traps should stay relaxed, with your arms fully extended gripping the barbell. This is your start position. Imagine then pushing the ground away from you with your feet and as you do so driving your hips forward and extending at the knees. To keep your spine neutral and shoulders back, also imagine that you are squeezing oranges into your armpits as you pull the bar from the rack. All the while exhaling as you do so. Pause at the top when you've reach full hip extension and are standing tall. Then return to the barbell to the rack with control, by bending your knees and driving your hips back , inhaling as you do so.