Yesterday, I was fine.

A good day; I had a laugh with my FP and was almost a normal person. Yet today, all I've done is sleep and I've been putting off the gym even though I know I should be going, don't feel anything and can't muster any sort of response to anyone. I get angry because people talk to me and I don't want to engage in anything. 

This happens quite a lot and as a Borderline and I wanted to know, what do you guys to combat the numb nothingness that comes and goes? Is there something that can be done to make me like the rest of the humans on days like these?