"I feel that if I try to motivate myself to just get it done (a little bit at a time) in the evenings, I will fail (like I have done so many times before). Every single weekend, I tell myself I will clean up, get organized, buy some groceries and start living a "normal" at-home life, and then every Sunday night, I feel like a failure because I haven't done it..."

so do it without getting motivated-and it`s better the HERE AND NOW then in the future.
do you feel sometimes like doing something? physical?
THEN do it!
are you a planning person? people who are orgenized tend to be. i think that we need to think of time to do things and instead of planing to develop more awaredess of ..."what do i FEEL like doing now?"
you may discover at certain momnets you WANT to do it. i think that oyu may have a chance...