Slack current and not bucking much wind. It's pleasant, I do it just for the row sometimes. Add current, a good bit of wind on the nose, another person and some gear, and it becomes exercise.

When the going gets tough (and that happens with a rowing dink!), I have a mantra: Slow and easy. Tempo is key, the timing of your stroke with the waves and chop. You hate to waste any of your physical amp/hrs.