Weighted Ab Wheel

Kneel on a pad, hands on the wheel's handles, wheel on the floor in front of you. Brace your core hard before you move at all, then roll the wheel forward, letting your hips extend and your arms reach overhead as your body straightens out. Stop before your lower back arches or sags -- that's your range for today, not a fixed target. Pull back through your core, not by yanking with your arms, to return to the start. The added weight makes the bottom position, where your body is most extended, the hardest point to control, so slow down there especially.