I was not able to unlock this after countless 10 minute sessions. So I used the free 20 minute Jillian Michaels: Kickbox FastFix Workout 1. It is a 20 minute workout. I didn't even 5 star all the drills, but I think there was about 6 drill challenges total in the session so enough to unlock this as long as you successfully complete the amount of FP required.
For people like me who were only doing the 10 minute workouts, I think 20 is the minimum session length that has enough drill challenges.