I play piano, and am teaching my brother to play, although he lives in NC and I in Michigan. I "give him lessons" via Skype and phone. When I'm at home, I make myself walk for at least ten minutes before I sit down to play the piano, then up again for another ten, then reward myself with more time at the piano.
I hope to soon be getting a dulcimer, and have yet to figure out a way to make that part of my routine of weight loss.
I frequently dance to CDs or the radio to add to my fitness minutes for the day.
I am a poet, so I have to make sure I have done all my exercise before I sit down to a long session at the computer. I have a blog, and co-edit and write on another, and in order to prevent these from turning into long sitting times. I interrupt them with walking, recumbent bike, dancing, or walking stairs so I don't get used to sitting too long.