Stand with your feet hip-width apart, then fold forward and place your hands on the floor in front of your feet - knees bending as much as they need to. Walk your hands out, one in front of the other, until you reach a full plank with your shoulders over your wrists and your body in a straight line. Pause, then walk your hands back toward your feet and roll up to standing. Out and back is one rep: the further your hands travel, the more your abs pay for the trip.

Works: abs, shoulders, hamstrings, lower back

Breathing: Exhale as you walk the hands out, inhale as you walk them back in.

Common Mistakes: Letting the hips sag as the hands reach the plank, taking giant lunging hand-steps instead of small controlled ones, and standing up with a rounded back instead of rolling up smoothly.

Make Easier: Bend your knees generously through the fold and walk out only as far as you can hold a straight line - the full plank distance can wait.

Make Harder: Walk the hands past the plank as far as you can hold, pause, and walk back - or move on to Body Saw or Up & Down Planks.