This is true.

This may sound counter-intuitive, but have you tried not trying to push those feelings away? What I mean is accept that your mood, in x time and y place, will almost certainly prevent you from enjoying the activity. Then you can decide whether or not your presence with your friends would damage their enjoyment. Your not being able to enjoy yourself will not always prevent them from having fun (sometimes it might).

Anyway, here's hoping the times of feeling a little better will appear more often.