Brain said:
If you want to have an impact for eternity or for billions of years, you're insane. Get your shit together and lower your goddamn standards.
If you want to have an impact for millenia, you will need to write or build something truly epic and groundbreaking and then cross your fingers for somebody to notice. That's unbelievably difficult, partly out of your control, and competition is at an all-time high. You can also become a mad emperor and command batshit insane funerary buildings for yourself (pyramids or terracotta armies). I'll let you think about how difficult that is, and ponder how much of a hindrance to progress that also is.
If you want to have an impact for decades, that's not too unreasonable, but the most important thing is to get noticed. You'll need either great talent, great luck, or great people skill to stand out from the lot.
I think you are seeing the pattern here: making an impact on society is fucking hard. Take any given length of time, multiply it by a thousand, take the inverse, and you'll get the fraction of people whose impact will last that long, and the worst thing of all is that these people's impact was partly due to luck. The direct consequence of this is that if you care about impact or being remembered, you are doomed to be miserable, not only because you won't succeed, but especially because even if you do, you won't know it before you're dead (especially true of painters).
Of course it's really hard. Nobody said it's easy. But it's also
possible. Quickly, name some people from two thousand years ago that continue to wield a (huge) influence in today's world. Surely you can come up with some names: Aristotle, Jesus, Confucius. Move closer to today's world and there are still plenty of people humanity will remember almost forever: Einstein, Newton, George Washington, Napoleon I, Alexander Fleming, Prophet Muhammad, etc.
Realistically, making an impact on the world so big most people will sit up and take notice for you and me is not likely. That doesn't mean we can't do anything though. If I went to Syria and died in pro-democracy protests, whoever is leading (or crushing) the revolution would get all the credit, but I would still have been part of one of today's more profound events. @jumpluff, maybe I'd come to regret it, but then I'd also be dead and dead people don't feel, right? I'm not going to go to Syria to die right now, though. I'm not sure that is what I really want yet, and there're still some things I want to do.
Now one could argue that there's no point caring about legacy, but what else
is there to care about? The whole point of creating new knowledge is to pass that knowledge on to the next generation. Works of art etc are for the same thing. Having fun is nice and all, but fifty years in the future are you going to care about how you peaked #1 on the DW OU ladder, or how many books you read? If you thought back to all your most memorable experiences, they would be something like your first kiss, your graduation from university, your wedding, a perfect score in a difficult exam and the magnificent sense of achievement that comes with it, etc.
Those are the things to remember.
Another example: after the 9/11 attacks on the US, many US citizens joined the army. They found a purpose in life - read
this, for example. If they succeed in the war on terror, they can look back on their life when they're dying and know they've achieved something. If they fail, they at least have tried. If they die, they die while living a dream. They have an significant purpose in life. Do you? Is your purpose in life to get as much fun as you can over everything you can? A year ago I would've said the purpose of life is whatever you want it to be, but said out loud that hardly seems like something I'd be proud of when I die.
I'm aware that my concepts are somewhat contradictory. Yes, I think of things that happen billions of years into the future ... and I also thing about what happens after I die, which is only a century into the future. I don't know how to resolve it. I guess in the long run everything is impermanent and there's nothing to aim for, but in the short run there's a lot that can be done. People do things that change the world everyday. I'm just not one of those people.
@GenEmpoleon, if I died today, my biggest regret would be not achieving anything with my life. As for my goals in life, they are massive and not easily achievable. One of my dreams in life is to win the Nobel Prize, but that's very unlikely to happen, isn't it? Am I happy? In some ways, yes. But in other ways, my life could be so much more.
Oh, the melancholy. zzz !