1) You might look inside yourself and think you know yourself, but over many decades you can change in ways you won’t see ahead of time. Don’t assume you know who you will become. This applies all the more to folks around you. You may know who they are now, but not who they will become.
2) You are more flexible than you realize. You may think now life that would not be worth living without your preferred city, career, partner, or hobby. But you really would adapt to most big changes, and have an ok life without most of what you now hold precious. Old folks with weak bodies and fading minds still love life.
3) Human lives are long. You might be unpopular when young, but with decades of work you could become popular when old. If you have something you are just dying to do, a lifetime can fit many failures before an eventual success. While it can be reasonable to take a few years of failure as a sign you might prefer something else, if this is really what you most want, you’ll have many more decades to keep trying.
That is some Grade A aging mojo right there…