In very long-term SSM's like TeaEarlGreyHot's and mine, the perspective changes in ways that is hard for others to understand. In my case, it's led to a situation where I know I can get through it, as opposed to initial feelings long ago when I felt "there is no way I can handle this in the long run!" And I take it just one day at a time and worry less about the long term. Perhaps I'm lulled into a false sense of hope...but like I said, I don't worry about it!
Part of the alterered perspective is that I'm somtimes amazed to realize that other couples actually have sex on a regular basis. I even shake my head for a moment and marvel, "how the heck do they pull that off?" "How does he convince her to sleep with him on a regular basis?" Etc. And then I realize, wow, my perspective has really gotten skewed.