I saw something recently on twitter which I can't find right now, but as I recall the person said they've learned to immediately look for weaknesses in every idea so that they think it through and discard them in a timely fashion if necessary so they can move on to other ideas without wasting time.
Personally, I have a stack of ideas that I've never gotten around to or followed through on, and non-programmers are always trying to tell me their ideas (for a revenue share!), but I only get traction when I think of something simply-scoped I want to try, often just to learn a tool or how to implement a particular thing, and then when it starts to turn into something that I like or other people like then it gets some momentum.