Bridge (Plank)

Get into the pushup position on the floor with your weight resting on your forearms and toes, your back straight and your head in line with your back, your eyes looking down at the floor. (You should be able to draw a straight line from your neck to your heels).
 
Pull in your abdomen as far as you can--imagine that you're trying to touch your belly button to your spine.
 
Breathe as you hold it in for 10 seconds.
 
Release, rest for a few seconds, and repeat. Try to hold the bridge position for a total of 60 seconds.