I put on my runners, or in the winter, my cross-country skies, and I go for a long trek.
I don't know if it's the abundance of fresh air, the lack of other voices, the unobstructed views, or the lulling repetition of putting one foot in front of the other but before long the tight knots of the problem loosen and the answer I was seeking floats up into my mind. In the past, I've used this technique to work through creative writing problems -- primarily those that crop up when I'm working on a personal essay -- but I've discovered recently that it applies to solving and setting cryptics, too.