There is no one answer. Standing up to everyone who sleights you in minor or major ways is not the answer, because it takes energy. Not standing up to anyone is also not the answer. Ignoring someone and not reacting is sometimes just as powerful as reacting, because your enemies or bullies don't know how to process that. Being sarcasticly friendly to your enemies can work too. I am old enough that I just don't have the energy to stand up to people much anymore. I have confronted people loudly and directly, played mind games with people, and there really is no one solution. Directly confronting people is also too predictable in a way. If you want to psychologically destroy someone, a predictable response "Stop doing this" etc. is just an obvious route that your enemies can be completely ready for. If you invade their space, stare them down, or a million other mind games you can play under the surface, that can be more damaging than the obvious "I AM CONFRONTING YOU NOW. YOU CAN NOT DO THIS! I SAW YOU DO THAT AND CAUGHT YOU AND I WILL NOT STAND FOR IT" There is no one answer. If you can not respond and appear not effected by someone, that alone could be more damaging than confronting them directly. If you call out every idiot who wrongs you, you will be wasting tons of energy, there are not enough hours in a day. If someone is going completely out of their way to mess with you, or destroy you repeatedly, I guess at that point you can use more extreme measures. I personally, even if someone has it in for me, would continue to play mind games, and mess with them in a subtle way. If you win some of these small battles, you can see it in your enemies eyes that you have won, and you don't need an army behind you, just creative ways to mess with them, to psychologically destroy them