A guy that I work with got me going on these Tabata style workouts. Its 20 seconds of as hard as you can go exercise followed by 10 seconds of rest, then repeat seven times for a total of 4 minutes. I do four different sets of different exercises with two minutes in between the sets. Perfect for my short attention span. It is a lot like a ski set, with the intensity of a short hard load followed by very little rest. I am coming back from a broken leg last fall and this has made a huge difference. Has anyone else on this site tried it? Thanks.