Rowing and running!
Metcon
Every 10 minutes, for 40 minutes (4 sets) for times:
40/30 Calories of Rowing
800 Meter Run
50 Double-Unders
Modify the workout appropriately such that you get between 2-3 minutes of rest between sets. The intent is smooth pacing and four sets that are very similar in time. If you are running over the 8-minute mark, scale back accordingly.