Keep after it, when doing a patch just ask yourself is it better than it was, Yes is usually the answer. It don't have to be perfect, most trucks aren't that's what gives them character , do the best you can with what you got, and enjoy it.
Here is a couple of songs that can lift you up and put a smile on your face ENJOY:
Jerry Jeff Walker Pick Up Truck Song
https://www.youtube.com/watch?v=RWK8GgWD4uA
Glen Campbell ~ I Love My Truck
https://www.youtube.com/watch?v=VGQNVq5Ou4E