Lack of Motivation

For about a year or so now, I can't seem to get back into motivating myself to exercise in some way. I start something for about a week or two, then I stop. Then a month or so later, I recycle the same actions... Then stop. I've been back on track with a more healthy diet, but I just don't know how to get myself back in the mood of getting fit. I'm not out of terrible shape and I've discovered this new found comfortabiltity with myself (in terms of my body)... I'm just stuck! As a promise to myself and my SO, I need to get back into the groove of things somehow. Anyone have any suggestions?