Rest between exercises is short, around 15 to 30 seconds, and the circuit is often repeated two to four times. This format keeps the heart rate elevated, ideal for boosting cardiovascular fitness ...

But coming out of it, I vowed to try and fit them into my fitness routine more consistently ... Kohn gave me a two-round bodyweight circuit with six abs moves. Why bodyweight?

Repeat that circuit five times with one-minute rest between rounds for a workout that lasts for 25 minutes (or slightly longer if you increase your rest periods). From a standing position ...