Plank: Get into a push-up position with your elbows and toes on the floor, while pushing the area between your shoulders toward the ceiling and keeping your stomach pulled in toward your lower back, to support it. Keep your buttocks tight and your eyes looking at the floor (ignore what your family is doing to distract you). Hold the position for as long as you can. If you can last more than one minute, make it more difficult by dropping your chin 20 times out in front of your interwoven hands, or by trying to balance on one foot.
Bicycle: Lie on the floor with your hands resting lightly behind your head. Raise your feet off the ground and bend your right knee and pull it toward your chest. Simultaneously twist your opposite shoulder toward this knee, keeping your elbows out of your line of vision. Switch sides back and forth. Keep your lower foot suspended in the air as you switch sides. Then hold to one side, reaching your shoulder toward the opposite knee for 30 seconds. Switch and then hold to the opposite side for 30 more.