On the Concept 2: 
1 min, 3 min, 5 min, 3 min, 1 min pyramid / 2 min easy

Pre-set the monitor for 23 minutes. Row five intervals in a pyramid of 1-3-5-3-1 minutes, with two minutes of rest in between each piece. Goal was to improve on the back half of this workout. The longer rest periods should allow you to get uncomfortable during each of these five intervals.