Set your monitor for a variable interval workout as follows, with no rest between intervals: 250m, 250m, 200m, 200m, 150m, 150m, 100m, 100m, 150m, 150m, 200m, 200m, 250m, 250m. Row the first 250m at a moderate pace, then 250m at an intense pace, then 200m moderate, then 200m intense, and so on down to 100 meters, then work your way back up to 250 meters in the same manner.