

To expand a bit on stubbornness: as I’ve said in another comment, invest your time on people who agree with the basic idea of your position but disagree with the conclusion.
When you go talk to those people, avoid telling your opinion. Use the Socratic method to make them walk step by step towards the conclusion (see this video, pay attention to how he poses open ended questions). This way, it’s the interlocutor arriving at their own conclusion instead of you pushing your ideas on them.
Keep in mind that whenever you start debating, you’ve lost the opportunity to make them see what you see. Debates are only useful if the target of your activism is someone listening to the debate.
Yes, these vegans are as irrational as people who refuse to eat human meat. “Ethical implications”, or whatever irrational thing they say.
I just need one reason to do something: it feels good, that’s how you know you’re being rational.