Arousal

So is it just me or do any of you feel that it can be difficult to motivate yourself to get in the mood to do the bedroom cha cha? Like some day I'm super motivated other times I almost feel annoyed when my s.o. is trying to spice up the mood. I also can't seem to motivate for round 2 or 3. Anyone else like me out there? I don't have a problem with sex my body just says no.