There have been times, I've walked in my garage and found that a certain task was calling to me, and I'd work on that and have fun doing it( whatta concept some times) all the while ignoring the other things I'd had to ignore , and feeling good about itOne thing that's helped me during numerous car builds is to not get stuck on a particular order of the builds. There of course are certain things that have to be done in certain order, or else have to redo steps if you jump ahead. But if I'm forging along on one part of my build and begin to feel overwhelmed or frustrated, I simply turn to some other part of the build, instead of walking away. I've done this many times to maintain my build, and my sanity when things aren't going well. Often times when I complete whatever other segment I turned my attention to, returning is easier, and I often come up with a solution to whatever made me turn away before.
I've built a lot of cars in my life, and this way of approaching them has made me stay interested over quite a few challenging builds.