[RossBencina]

Something I've been trying for the past year or so is adopting the following mindset: "I'm going to stay on this direction until I prove to myself that it's going to work or I prove that it's not going to work." By "prove" here I mean semi-formal things like characterising the problem and the chosen direction well enough to say with high certainty whether or not it's going to work or is futile.

One upshot of this is that it forces me to be clear about the definitions of "going to work" and "not going to work." It's related to definition-of-done in some agile methods, and also to "imagine the problem as solved and work back from there," which is one of the heuristics Polya talks about in "How to Solve It".