Complete 32 intervals of 20 seconds of work followed by ten seconds of rest where the first 8 intervals are pull-ups, the second 8 are push-ups, the third 8 intervals are sit-ups, and finally, the last 8 intervals are squats. There is no rest between exercises.
With a continuously running clock do one pull-up the first minute, two pull-ups the second minute, three pull-ups the third minute... continuing as long as you are able.