300 reps for time, following the pattern:

20 seconds of pull-ups
10 seconds of rest
20 seconds of push-ups
10 seconds of rest
20 seconds of sit-ups
10 seconds of rest
20 seconds of squats
10 seconds of rest

After the round of squats, begin again with the pull-ups. Keep a running total of reps and continue working until 300 reps are completed.