What keco said, looks a bit funny but it works. Plus squats if you have a fitness ball put it against the wall with the ball sitting in the small of your back and bend your knees with a straight back til your legs are 90 degrees. At the moment I do 2 sets of 20. Also I heard Beyonce stands and clenches her but for like 30 seconds every day, I'd imagine a few times a day at that! lol