This is really important. Being young is cool not just because your body works better but because you still have a lot to discover. Discovery is fun. Experiencing something for the first time is fun. But the problem is that you can only experience something for the first time once. The second time it might still be fun, or the third time, but by the time you do something 100 times or 1000 times or 10,000 times it becomes less fun. This is one of the major differences between doing something as a hobby and doing it as a job. When it's a hobby, when it stops being fun, you can just quit. And sooner or later, everything stops being fun if you do it often enough.
The problem is not that we don't live long enough, the problem is that most people don't have the freedom to do the things they want to do in the time they have. That is a much more tractable problem, and it is the one we should be working on, not extending life spans. If you have the wherewithall, ~100 years is more than enough time to get sick and tired of everything.