Use a deck of cards to determine your reps, says Kent Pumpa, owner and director of Boot Camps Australia. Pull a card and do the number of reps indicated. Face cards are worth 10; aces are worth 20. Assign a different exercise for each suit of the cards. Draw a new card for each move.

Flip a coin before each exercise, says Jonathan Cawte, exercise physiologist,trainer and owner of Aspire Health & Performance in Sydney. If the coin comes up heads, do the first strength exercise as instructed. If you get tails, take yourself off on a 30- to 60-second sprint. Repeat as you move through the circuits.

Grab a workout buddy. While they complete a circuit exercise, you sprint an agreed route. Your partner has to keep up with the exercise until you return, says Pumpa – so the slower you run, the longer their torture! Next, swap. Alternate as you work through each exercise.

Roll a pair of dice before each circuit, says Cawte, then add a zero to the end of each number. The first die tells you how many seconds to do each exercise, and the second tells you how much rest to take afterward.

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