I'm glad I'm not the only person who has #3. For some reason, I seem to get miraculous insights into problems when I'm exercising, so I've taken to keeping a tiny pen and a couple index cards within reach at all times. While running, this has sometimes resulted in me crouching on the side of a street, scribbling madly while constantly looking for oncoming cars, but when I get back home and finally finish that tricky proof or implement that evasive idea into code, I find it is well worth the trouble.