Lie on the floor with your knees bent, a dumbbell in each hand pressed straight up over your shoulders. Lower them until your upper arms touch the floor, then stop -- the floor cuts your range short well before your normal bench depth, taking the stretched bottom position out of the lift entirely. Press back up smoothly from that dead stop rather than bouncing your elbows off the ground. Without the stretch at the bottom, more of the work falls on your triceps locking out the top than on your chest, and your shoulders sit in a safer position than a full-range bench press. Keep your feet flat and your lower back relaxed against the floor.