Stretch those arms out, way out. Then bring them back in. If this exercise feels good, do it slowly for ten times. That should get the blood circulating. Monotonous, tedious tasks such as volume keyboarding are stressful.
Exercise is needed in any task, particularly stressful task.
However, although it is fun to stretch your arms, when typing, keep your elbows close to your body. You need to be relaxed to develop speed and accuracy. Use the flash card option in NimbleFingers to build up speed in typing common words and phrases. Start with simple, two letter words, then progress to three letter words, four letter words, and then five letter words. But after that, give it up.