There is no intrinsic value in finishing something, except for the opportunity to start something else.
Completism leads to lethargy.
The desire to be "all done" with something is the failure to appreciate the process. The center of value doesn't belong at the end, but in the middle.
I’m not sure how to relocate that center, other than to constantly remind myself of where it belongs. And, I suppose, to practice deliberately enjoying the process of things, instead of waiting for, or rushing to, the end.