Anecdotally, I still wind up stopping because... I'm a lazy bastard. Feeling like you've failed on a random project that you talked about is demotivating, so I can see the point both ways. I renovated my master bathroom several years ago and had talked about it at work, but I'm lazy ;) so it took about a year to complete. Being the butt of the "so how's the bathroom going ;D" joke at work did not really help my motivation on it, having an upcoming wedding and needing to get it finished did.

I've been working on doing only one project at a time, which has helped with my success rate and self worth. I still think about several and have a hard time focusing, but I try not to talk about them until they're actually in progress if at all.