Bodyweight Exercise: Six Inches
Six Inches is a simple isometric exercise to work your abs.
Step 1: Lie on your back. You can place your hands at your sides, or under the small of your back for extra support.
Step 2: Keeping abs tight, lift feet six inches off the floor and hold.
You can do one rep holding this position as long as possible, or you could start with three reps of 30 seconds each, and work your way up.
Six Inches video:
See more exercise guides in The Bodyweight Exercise Collection.