I love that analogy. No, you’re not going to personally save the world by reducing your carbon footprint. But you know what you are going to be? One leaf on a tree in a forest, making that little bit more oxygen that helps collectively make the world a better place.
And that’s worth doing. Especially if you can encourage other people to be leaves too.
Overall, I just try to be better than average for people in my area. If everyone did that, we’d keep moving the average to a better point. I don’t need to completely upend my life for ultimately negligible impact, but I refuse to be the problem.