Here is the start, there is the finish line. Between that, you have to run.
There's an old adage that for every second too fast per mile in the first half of the race, you'll run at least 2 seconds slower at the end.
Find a way to enjoy parts of every run. Most of your runs should be mostly enjoyable.
When I finish a run, every part of me is smiling.
We have a no puke rule. The purpose is performance, not puking.
We are designed to run and we increase our chance of daily happiness when we do so.