Accountability - how to get it?

I just finished reading the book The Four Tendencies by Gretchen Rubin, and I have found that I am (unsurprisingly) an Obliger. This makes sense for most areas of my life, including why it's so hard for me to convince myself to workout and eat right.

I've never been one who likes working out along side others: I'd much rather be alone in a room doing so. But i do find it true that I have this need for my habits to matter to someone besides just myself. And instead of trying to fight against the grain on it this time, I'd like to try and work with myself on this tendency.

Most of the friends and family I have aren't reliable enough for me to ask; they typically stop a habit quicker than I do.

Does anyone have an idea of how to create an accountability group/other ideas of some sort?