Lie on your back, and open your legs into a diamond shape (aka butterfly legs) with the soles of your feet pressed together and knees out wide. Extend your arms overhead. If you have an AbMat, place it under your lower back for support.
Inhale to curl your torso up, and tap the floor in front of your feet to stretch your glutes a bit.
Slowly lower back to the starting position.
This counts as one rep.
Do as many reps as you can in 40 seconds, followed by a 20-second rest.