Stand upright holding a dumbbell in each hand, hands at the front of your thighs, with your knees slightly bent.
Keeping your arms straight and knees slightly bent, slowly bend at the hips (not your waist) and lower the weights as far as possible without rounding your back, which should remain straight. You should feel a nice stretch in the back of you legs.
Squeeze your glutes and keep your back straight as you return to standing to complete one rep.