I agree focusing on the journey is more healthy (many cognitive therapies focus on trying to re-frame your thinking like this), but realistically all of our social/rewards structures are focused on the outcome, hence it's so difficult to detach from it.

If we could detach from the negative connotation of being "non-ambitious", we could reason like this: am I less likely to become a millionaire if I don't obsess over it? Yes. Will I be OK even if I don't become one? Yes. So I'll give it my best shot, but I won't sacrifice the rest of my life for something that might not happen even if I did obsess over it.