I'm a great believer in the theory that each function holds a different, specific role in the typological set-up of the 16 types.
And you are spot on for me (INFJ). I get great relief from figuring out solutions to problems using my tertiary Ti. If I'm presented with a stressful situation in real life which has no obvious or immediate solution, then I'll seek relief by solving crossword puzzles or playing logic games on my PalmOne device.
Costrin has it right, though, when he warns of the danger of overindulging the relief function. It happens to me quite a lot, as I am forced to overuse Ti in my job. Either I get stuck in analysis paralysis and become incapable of making a decision, or I'll play my logic games to excess and totally neglect the more important stuff I'm supposed to be doing.
In fact, I'm doing that right now, by participating in this thread instead of getting on with my work!