Do you ever think about your past lusts/crushes/exs?

One girl I dated for a few weeks when we were both 16, we broke up, because we were both waiting for the other to take things up a notch. Damned middle class British reticence. I met her again (through work) about 10 years later, and she was hotter, and funnier, and we got on well. We were both in solid relationships at the time so nothing happened, but I spent a while wondering.

Other than that, some encounters I remember fondly, but as I get older I realise that far more of the responsibility for them being exes resides with me than I used to be able to understand, or accept, so I can't really fantasise about fucking them now, without reminding myself that I fucked them over then.