Exercise Advice: Stand with your feet beyound
shoulder width apart and place an exercise ball between your middle
back and a wall (see illustration). Using the exercise ball as support,
begin this exercise by squatting as though you are going to sit
down in a chair. Squat to a point to where your thighs become parallel
to the floor and then return to the start position. It is very important
that you keep your back as straight as possible throughout this
movement (one way to help do this is to focus your eyes on a spot
high on the wall in front of you throughout the entire exercise).