A theme I have been mulling over and as often is the case- reflected back in comments and posts by others here ( synchronicity / pattern recognition, or whatever)- is: Expectation. No surprise.
I think that the more tightly one holds onto the mental image- of what they hope to get back from their effort and involvement, the more likely they will fail to recognize opportunity and value in ways that are not promoted or originally assumed. Some pursuits provide indirect benefits while others help to form bridges to new opportunity that may have more noticeable benefit, which might include - perspective.
Chance for survival is an obvious motivator when in dire need. The rest of the time I think it is every other Possibility that keeps people going. It could make a fool out of me as it has before, but I also know that it is part of being happy. "living" And not taking too many things too seriously.
How can you enjoy the trip if all you think about is an end result that is sure to differ from a rigid expectation?