leg lift pushups
26 reps each side
Get into table-top position, with the hands under the wrists and knees under the hips. Core is engaged to make the back straight. Lift the left leg out behind you, creating one nice long line from shoulders to foot.
Touch the forehead to the floor and come back up, like you are doing a push-up. Do this 26 times.
Switch legs and do 26 more.