You say you're active in your club--maybe that's one of the reasons you're losing motivation. You just get so engrossed in it that it becomes more of a job. Do you feel guilty if you don't ride your bike to meetings? Do you end up riding less because you're taking care of club business? Just a thought.
Me, I just look around me and see all the out of shape people. Like, my dept went out to lunch yesterday and DROVE to a restaurant that's across the street and in the next block. I was walking back afterward and one stopped to ask if I needed a lift! Just look around. Call it fear or pride, but it keeps me going.