sometimes ... things can really pile up on you...
and it can get so frustrating. Lots of times you can hit this flat spot... where you don't feel like doing anything at all. I"m not sure that's what you mean, but I can understand how you might feel lack of motivation...
Just remember... things might feel tough now, but, they can get better if you keep working for it. If there's something specifically related to writing, or something you used to enjoy, try to remember what made you enjoy the activity in the first place...
good luck
and sorry this post is ... confusing I'm a bit tired and not thinking the best right now ^_^