Guilt is the product of knowing from the inside you did something wrong, and needs to be corrected. I would say that you have, likely unknowingly and not on purpose, replaced practice with something else. I know this from experience. This week, i didn't practice because i replaced it with excessive yard work, house projects, and working on race cars. My problem is that my hobbies sometimes clash. One night, i got run off by the bugs, plopped myself on the couch, and watched TV. I could have picked up my guitar, i didn't, and felt guilty. I felt guilty because i really want to learn how to play it, i know learning comes from practice and diligence. The next question would logically be, how bad do i want it?