Super Geek:
I used to . . . try to guess exactly one minute when I used to take public transporation regularly. Mind you, I don't bore easily. Myself, at least. I would look at my watch, note when the second reached 0, 15, 30, or 45, and then I'd go back to staring off into space. Then I'd try to look at it again in one minute, +/- 5 seconds.

+ or - five seconds is what I considered successful. If I guessed a minute was more than 65 seconds, then I thought my mind's current sense of time was too slow. If I guessed a minute was less than 55 seconds, then I thought my mind's current sense of time was too fast. The idea was to keep doing it and compensate for my wrong sense until my mind's sense of time was properly "calibrated".

You have no idea how freaky it is when you hit the minute on the second five or six times in a row, which happened only once. You're not counting, you're just trying to "feel" this very specific length of time. It doesn't seem too hard, it's only one minute, but to hit it precisely certainly is not a given.

Sometimes I would think consciously about it, asking, "now? now? now?", but it was surprising, or maybe not so surprising, how many times I'd start thinking of something else and then spontaneously snap back and look and it would be on the exact second.