I think the longest I ever went, was two weeks. That was this past summer, but I had very good motivation, in the form of a girl I was staying with.
She had gone out of town to visit her parents for a couple weeks, and I was, umm, "saving up" for her return.
Even knowing what awaited me on the other side of that window, it was extremely difficult, and was actually getting to the point that I was beginning to experience physical pain. This wasn't helped at all, by her suggestions that I check out certain "adult" titles, in her rather massive video library, while she was still away.
I wonder if we could form this into a competition of sorts. You know, to see who lasts the longest. I surely don't think it'll be me. I wonder what the prizes/penalties could be...