Willpower is a muscle, but at any time one also has a finite quantity. I'm using and building mine elsewhere these days. In the meantime a crutch that pushes me in a positive direction is useful.
Oh absolutely. You don't start out doing 100 push ups. You start out doing 1.
Anything to help you while you build up endurance is great.
But the bottom line is you've gotta get to the point where you automatically consider every purchase.. and that's not in a taxing way, it's in a way such that basically everything is rejected, cause your filter is so high, and then those few things that you decide you actually want, you consider if you need them.