Keep your torso upright and ensure the front knee does not go past the toes. Return to the starting position and repeat with ...

We're going to do a 10-minute, total body workout using the stability ball ... Now we're going to move on to hamstring curl. Lie back, heels on the ball. Raise up, nice, straight body.

Repeat for 6-10 reps. Perform the same move as the double-leg stability ball hamstring curl, only this time, use just one leg ...