A few Saturday mornings ago, we did this conditioning circuit. Although people were huffing and puffing at the end, they said they really enjoyed it. It can easily be done at home.
Spend 45 seconds on each exercise with 15 second between exercises:
Jump Rope
Russian Twist (with ~25lb weight)
Push-ups
Squat with alternating kicks
V-ups, or any other core exercise
Lunges
Punch burst—as fast as you can with good form, not necessarily as hard as you can
Repeat as many times as you like, resting between rounds.
Enjoy!