It's because you don't value yourself enough. You are other-directed. You'll do things for others that you won't do for yourelf. You take care of yourself like you should, when you know your therapist will be asking about it. You know what to do, you just don't bother to do it when you pereceive you don't have to.

This would make a really good therapy topic--ask your T the question and get him/her to work through the answer with you.

PS. I sense this, as I can be very, very much like this myself! Understand what you are going through!