Dive in
I often bump into people who want to do something big, interesting, or important, but who utterly lack the ability to commit themselves to a particular action (often because they lack the ability to convince themselves that something is worth doing).
My suggested remedy comes in three parts. First, become able to feel conviction even in the face of high uncertainty. Second, learn how to weigh your options so hard that by the time you've picked the best available action, no part of you has an urge to go back into "deliberation mode" until you encounter new evidence or ideas that would have changed the result of your deliberation. Third, come to realize that you find good things to do by getting your hands dirty, not by sitting on the sidelines and bemoaning how no task seems worthy of your conviction.
Imagine two high school students, Alice and Bob, both of whom want to make a big impact on the world. Alice says (in an excited, breathless voice) "I'm going to change the world by starting to work for company X, which will give me skill Y, which will make me attractive to company Z, and in company Z I'll be able to work my way up the ranks until I have the clout to get onto a committee at the United Nations, and then I'll work my way up to president of the United Nations, and from there I'll be able to make a real difference!"
Bob says, "That plan sounds stupid and will never work. Also, even if it did, the UN has no real power. I also want to change the world, but I'm not going to do it via a long convoluted hopeless plan. I'm just going to generally improve my ability to change the world and wait for a better plan to appear."
Bob is correct, in that Alice's plan is in fact hopeless. But I still have my money on Alice doing more good than Bob, in the long run.
Yes, her plan is bad. It's complicated, it has too many steps, and it's built on a poor model of how to change the world. But I'd still place my money on Alice.
Why? Because Alice is going to be out there bumping into the world, and Bob's going to be staying inside wishing he had actions he could commit to. Alice is going to have dozens of opportunities to realize that her plan is bad as she struggles to work her way up the ranks with her eyes set on the presidency of the United Nations. If she's sufficiently good at updating in response to evidence and truly changing her mind, then she'll realize that her original plan was silly, and she'll find better plans. And because she'll have been out there in the wild, bumping into social constraints, running into other enthusiastic people, and stumbling upon new opportunities, she'll have more chances than Bob to put herself on a good course of action.
Bob won't get that feedback loop when he sits at home waiting for better plans to appear.
The only way to get a good model of the world inside your head is to bump into the world, to let the light and sound impinge upon your eyes and ears, and let the world carve the details into your world-model. Similarly, the only method I know of for finding actual good plans is to take a bad plan and slam it into the world, to let evidence and the feedback impinge upon your strategy, and let the world tell you where the better ideas are.
As an example, consider Elie Hassenfeld and Holden Karnofsky, co-founders of GiveWell in 2007. GiveWell originally focused on evaluating short-term interventions on global poverty and global health. Nowadays, those two are also heading up the Open Philanthropy Project looking at riskier and (I think) much higher impact interventions. In 2006, when Elie and Holden were considering staring a charity evaluator that focused specifically on evaluating global poverty/health charities, you could have gone to them and said "Actually, I'm not sure that's literally the best thing you could be doing. There are better ways to do good than just helping people out of poverty, we have animal suffering and existential risks and other such things to worry about." And you may well have been right. But it wouldn't have been helpful (and, knowing those two, you wouldn't have gotten very far). The way that Elie and Holden got to where they are is not by agonizing over whether a global poverty charity evaluation was literally the best possible thing he could be doing. They got to where they are by jumping directly into the fray and doing something. They saw that charity evaluations were crap, and jumped into the space head-first. Because of this, over the years, it was Elie and Holden — and not the person who said "hey wait this might not be literally the best available choice" — who learned the ins and outs of the charity landscape, made important connections, gained visible credibility, built a team of brilliant people around them, repeatedly encountered new evidence and changed his beliefs, and ended up at the helm of a massive collaborative project with Good Ventures. By now they've had a huge positive impact on the world, and are poised to continue that streak.
In my experience, the way you end up doing good in the world has very little to do with how good your initial plan was. Most of your outcome will depend on luck, timing, and your ability to actually get out of your own way and start somewhere. The way to end up with a good plan is not to start with a good plan, it's to start with some plan, and then slam that plan against reality until reality hands you a better plan.
It's important to possess a minimal level of ability to update in the face of evidence, and to actually change your mind. But by far the most important thing is to just dive in.
How, then, do you dive in? Which fray should you leap into, and how? Unfortunately, I don't have a great answer to this question. I attempted to leap into many different frays many different times, and most of the time, I bounced off. One day I'll figure out how to transmit more of the lessons I learned, but for now, the best I can say is this: It helps to have a concrete plan (even if that plan is crazy).
Maybe the plan is "I'm going to befriend my senator, and become an aide, and work my way up the ranks, and eventually become a senator myself, and then I'll have a shot at becoming the president." Maybe the plan is "I'm going to get a biology PhD so that I can start my own CRISPR lab so that I can be on the forefront of human intelligence enhancement." Maybe the plan is "I'm going to become a project manager at DARPA, and put in a lot of effort into figuring out who the real decision-makers are and where the real power comes from, and then I'm going to follow that trail." Maybe the plan is "I'm going to read the AI papers from all the separate subfields, and have a better picture of the field than everybody else, and figure out how to ensure that the first AGI humanity builds is aligned using my own bare hands."
The idea doesn't have to be good, and it doesn't have to be feasible, it just needs to be the best incredibly concrete plan that you can come up with at the moment. Don't worry, it will change rapidly when you start slamming it into reality. The important thing is to come up with a concrete plan, and then start executing it as hard as you can — while retaining a reflective state of mind updating in the face of evidence.
If it becomes clear that power within DARPA is nepotistic or otherwise well-defended, maybe you'll switch tactics, and maybe you'll have a much better idea of where you could actually make a difference, now that you have more connections inside DARPA and a better understanding of the landscape. If you realize that you won't be able to understand what all the disparate AI subfields are doing just by reading their papers, maybe you'll decide to shift tactics and apprentice under as many people as possible. Your second plan doesn't need to be good or feasible either, of course — the important thing is that you (1) start with a plan; (2) get out there and start operating; and (3) get better plans as you get more information.
You're still going to need a lot of luck, and you need to be prepared for many of your plans not working. Also, don't get me wrong, it helps to start with a good/feasible plan. But "quality of the initial plan" is much less important than many people expect.
(If you want help putting your initial plan together (or building your initial network), I suggest applying to a Center for Applied Rationality workshop, they're good at that sort of thing.)
The important thing is to stop waiting on the sidelines for better options to appear, and to start leaping in there. Make a crazy detailed plan, and dive into the fray.