This Wasn't in the Brochure is a floor-based cardio workout that looks manageable on paper and turns on you almost immediately. Push-ups, high knees, climbers and climber taps cycle through seven stations per set - and the rep counts are deliberately deceptive. Two push-ups sounds like nothing. It stops sounding like nothing around round three.

The structure keeps you moving between the floor and standing, which is exactly what makes it hard. Every drop into a plank and every pop back up to your feet is work your heart rate pays for, on top of the exercises themselves. 

Climbers dominate the middle of the sequence because they are the great equalizer - shoulders holding your bodyweight, core resisting rotation, legs driving like pistons, all at once. The climber taps wedged between them break the rhythm just enough to make the next ten feel brand new. High knees bookend the plank work, forcing your legs to sprint right after your shoulders begged for mercy.

Keep your hips level during climbers - if they pike up, you are resting, not working. On push-ups, lower your whole body as one plank, chest and hips together. During high knees, pump your arms and stay light on your feet; heavy landings drain speed you will need later.

You signed up for this. Nobody said it would be pleasant. That is why it works.

Make it Harder: Speed up the climbers while keeping your hips level.

Make it Easier: Do the push-ups on your knees and march the high knees.