Congrats, lilypup!
I have almost no one to cancel on, but agree with Christina. Really try to force yourself to go whenever you can. It can all too easily become something that feeds on itself. What wiretwister said made me wonder if maybe you too have a kind of pattern of certain days you're really disinclined to be out. If so, scheduling for other days might help. Doesn't matter if it seems everyone sees (for example) the relief of TGIF in going out. If TGIF brings to your mind, "ahhh, home", you'd probably not exactly be setting yourself up for success if you were to schedule things for that night.