I can certainly relate to some of the responses, in this thread. Change is a given in our lives, you either move forward to go backward. Staying put is not an option. If you do the same thing long enough, burnout always seems to rear its ugly head. Since I've been building hotrod cars and bikes, for almost 50yrs, I've learned to deal with some of the issue, by having more than one passion/hobby. During the Winter months, I indulge my firearms passion by building custom weaponry and hitting the range, with my wife. During the warm months, either my Elco or my custom Harley get my attention. My wife and I are both Admins for a couple of Facebook groups and I'm also a Mod for the Team Chevelle site so both of us spend way too much time, online.
Being retired does have its advantages.
Bottom line, put your project on hold, for awhile, if need be. Selling it almost always causes remorse. Lord knows, I've sold a ton of vehicles I really wish I had,back.