Constantly being told "you are the future" by teachers, friends and family members is overwhelming. Especially after 18. You have new responsibilities and the stakes are higher for you. There is pressure in your family/school/community that makes you consider if you want to start a family or go to an Ivy League or get a really high-paying job. Whatever it is, it suddenly becomes our responsibility to "change the world" (ugh-daunting). Ultimately, something along the lines of the following fearful thought eventually strikes you:
"What kind of future am I putting forward?/I don't even know what I want and everybody somehow wants me to revolutionize mankind. How am I supposed to change the world for the better? I have no influence, blah blah blah."
(sigh)
Well- you're not. If we're going to get technical, you don't have to do anything after 18 outside of what you want to do. That doesn't mean you should spend your time doing nothing, but the reality is that the pressure to change things (in my personal opinion) comes from the society with which you are connected. How resilient you are to that society is also up to you, depending on whether you are willing to do as you are told or not. How you were raised, your background, and your lifestyle really contribute to that. What I've found interesting is that whether you want to affect the future or not: you have, you will, and you already do.
Think about it. There's something in your past that has made you promise you would act differently when you were an adult, or something that you decided was so good for you that you were going to make it a part of your everyday life. That decision is you pushing forward a certain path, and ultimately framing your world. If you don't recognize the "when I grow up I will never" thoughts, I can attest that you are probably lying.
Regardless- maybe "the future" is the future specifically belonging to you. It certainly makes it easier to change "the world," also known as your world. In essence, consider the message of this notoriously stressful quote being one that means "you are your future." Technically, it's been what helps me find my center. Here's my logic:
Humans by nature are sort of self-important. Superiority over nature (environmental waste), other people (Anti-semitism, discrimination), and etc., were once just ideas. Once we're grown, we develop this bad habit of refusing new ideas; concluding that my way is the only way. Every way of doing something that isn't my way is WRONG because the way (my way) has to be right. It hurts the ego and bruises the dignity anyone with convictions, and for some reason, I have yet to discover I feel we prioritize that more than we do to better our circumstances. It has become so important to feel right that we no longer care if there are long-term benefits, much less what they are.
And yet, we doubt ourselves. We, a superior human race that is so right and important all the time, still feel like we have no influence. One kid polluting the environment gets it into their head that just one person isn't going to effect anything, and applies the reverse logic when electing the leaders of a country. That same kid thinks "well that another person is going to change everything". Tell me in what world that makes sense.
We free ourselves of the responsibility to change everything by putting it on someone else and try to focus on changing everything related to us instead. It makes it easier to have dreams, set goals, and be ambitious. The way for us to change "the" world/future is to foremost change our individual futures. I think a local approach can be a way to band together ideas, rather than tearing them down. It just has happened with the Dakota Access pipeline, it's happening with people who choose to recycle (sort of shaming people who do not), and it's happening whenever you want something.
My point is, I think finding what you want to affect in your life makes the most sense and provides the most effective path for doing big-scale things because you connect with like-minded people. But what do I know, right? I am 'just one person.'