This workout is meant to be an ALL-OUT 4 min sprint! Just sit-down, shut-up, push hard and holdthehellon!
If you are pacing yourself during the 4 min, you are doing a different workout than we posted.
A lot of folks will be doing the v-ups on the box. You know, that sit down and lift your legs thing while you crunch? That's all-good, but you'll get more out of it by running to the mat, or just dropping to the floor and doing REAL Vs.
Vets might need more weight for the triceps. Then again, if your tris are smoked from monday switch this move for a cable push-down.
If your HR isn't in the sky (or, if you are feeling froggy) during the KB couplet, consider a bigger KB 35/55.