I'd suggest gardening except that I know that's not exactly practical at your place. I find that having something to do with my hands really helps with that kind of antsiness. So some sort of craft? You could get yourself a big box of sculpy and go wild -- brainless and fun! You could model yourself your own little Promethean Age play set. (-:
There are also a ton of little tiny museums and historical sites around New England, all of which are hurting for the $5 or whatever that each visitor brings. That might be too close to thinky-fun though. There's MassMOCA. There's also longer-excursion things like Acadia and Bar Harbor, Hammond Castle in Gloucester, Pergatory Chasm, etc.
I dunno what else to suggest. Do you know if what you need is more the getting out, or the physical activity?