I've swapped planes for trains, omnivore diet for vegan, I travel by bus in my everyday life, and am a member of a car collective for those few times a year I actually need a car myself.
I don't preach any of these things, but I talk about it / mention it when it's brought up. Everyone somewhat close to me knows about my lifestyle. My philosophy is to show it's not only possible to live like I am, but that I can still enjoy my life to the fullest in doing so.
I also support local organisations and political movements financially, and vote for the parties I believe have the best plans for the future.
I was a huge Taylor Swift fan until she knowingly started dating a racist, sexist dirtbag. Dating someone with such views means you excuse those views. I was and am not willing to financially support someone with those views.
I also used to fly a whole lot. Probably once or twice a month on average. I developed a bad conscious about it and just stopped. I allow myself to fly if I absolutely have to (has happened twice so far), but otherwise I only travel by train or bus. My vacation destinations have changed quite a bit, to say the least.