DS7 has DCD and also has trouble sitting and writing. The OT suggested to make sure he has support for his feet (i.e. feet not dangling) - this seems to help a lot. Also taking mini-activity breaks during a task seems to help.

She also suggested doing a little warm-up before doing a task like writing. Some of the suggestions were:
* Push on wall as if to move wall
* Lean on desk for “desk push-up”
* Do “chair push-up” in sitting by lifting bottom off floor or chair, holding self up with arms
* Weight-bearing through arms via wheelbarrow walk, crabwalk, bearwalk, etc.

DS was doing some core exercises at school this year, but I don't know exactly what they were. He enjoyed them though.