I had an almost lifelong habit/compulsion from when I was about 4 until I was 50+ and it was a bit part of why I was in therapy. I remember in my late-20's trying to imagine what my life would be like without the compulsion (which took up 5-15 hours of each day) and utterly failing; I couldn't imagine what I would "do" in that time if it weren't the compulsive behavior.

I think therapy is a bit like that; I was in therapy, twice, for 9 years with the same therapist and could not have imagined what life would be like after therapy. Therapy made my compulsion unnecessary to me in my early 50's and now (I'm 60) and I finished therapy when I was 55 and have trouble remembering life with the compulsion or what it was like in the beginning of therapy. It's kind of like when you are sick, you can't remember being well and when you're well, you don't remember the pain of being sick.