I get caught up with it sometimes also..At times at the end of the day I look at what I've done and say,"What a piece of s---".
Then after being away from it for a few days I look at it and say," Wow this truck is going to look great". A lot of it is in your head.
Have a plan..and only work on the truck when you feel like working on the truck..Forcing yourself to work on it to meet some deadline is really not enjoyable and can produce lack luster results..
Keith