Position yourself with your back on a flat bench and feet firmly on the floor. Place your hands up on the bar using an underhand grip slightly wider than shoulder width apart. Take a deep breathe in, extend the elbows and lift the bar up off the rack until elbows are extended but not locked. Slowly lower the weight directly down to your chest, inhaling as you do so. Pause when the weight is just above the chest, then press the bar directly up again, exhaling as you do so and squeezing your chest muscles. Repeat for the number of reps or time required before re-racking the barbell.