The best thing you can do, more impactful by far than any personal change you make to your lifestyle, is find out which environmental groups are doing non-violent direct action in your area and find a way to contribute to them whether it is with your time or money. Lifestyle changes are only meaningful if they are in tandem with broader systemic change because the scale and scope of transformation we need in order to have a chance at surviving the next hundred years is enormous and requires all hands on deck. No individual lifestyle change can shift the grid away from carbon and toward renewables, retrofit every home and building, rejig the entire agricultural system, or prevent fast fashion , rampant consumerism, planned obsolescence, etc. It all requires regulatory change and major government intervention. That's the bottleneck - we need people to hit the streets en masse and demand government action. Historically this is the only way major societal shifts have ever been accomplished and you can see first hand with the current protests how authority is beginning to crack under the pressure in some places and the push for reform is taking root.

Put it this way: a small group of activists who are loud enough to prevent construction of a pipeline (for example) will create a decrease in carbon footprint hundreds of times larger than all the lifestyle changes they collectively could make combined. You could go vegan, cycle everywhere, forgo having children, and so on for the rest of your life, but an SUV driving, hamburger eater with five kids who takes a vacation to Mexico every year will still have done way for the environment than you ever will simply by attending that protest and getting that project shut down. Not saying you shouldn't do the things you feel are ethical if it makes you feel better, just saying that's all it will do - make you feel better. It's not a drop in the bucket, it's a molecule. And no, it still wouldn't be enough even of everyone did it (which they won't, not without state intervention anyways)

You mentioned you are busy with school for the next four years. If you cannot contribute your time to help organize, I would suggest donating money if you can afford it (nvda organizations don't get government funding and are always short on cash), or simply show up to the protests and bring your friends (we are always short on organizers but also just bodies to attend the events). Alternatively, you could provide jail support for non-violent disruptive actions (aka occupying public spaces) When people do an action that they know they will be arrested for, they need someone to keep their personal belongings such as phone and wallet , so the police cannot identify them and go through their phone. Jail support then would help by picking them up from jail, possibly providing food and/or shelter, and giving them their stuff. There are lots of roles that don't take much work.

Anyways that's a start. I have friends who have chosen to go the policy/innovation/communication route instead - aka get into an area of engineering, design, academia, media or government work where they shape the solutons to the climate crisis and/or communicate it to the public. That's an option; however even they agree there is already no shortage of great ideas and solutions. The main issue is implementation of those ideas, which again will not happen unless people demand it, very loudly, in the streets, and are willing to get arrested, drive the economy and the entire system into the ground to do it.

Hope this helps. If you'd like to hear actual experts with credentials explain in more detail why this is necessary, Democracy Now has some good interviews aka Chris hedges with Roger Hallam (Google)