mmaxe01, I have a little tip: Gently select a villager who is exercising (without picking her/him up) and then keep an eye on the status bar. If s/he gained skill, a message that says something like "Your villager improved in construction" will appear. If no skill was awarded, the message will be "The villager wasn't successful this time" (along with the villager shaking her/his head and saying "no" or "uh-uh").

I micromanaged my villagers' fitness regimens for about an hour to get enough trainee builders to push the statue - they should all be ready for the Boston Marathon by now!