Give up defining yourself - to yourself or to others. You won’t die. You will come to life. And don’t be concerned with how others define you. When they define you, they are limiting themselves, so it’s their problem. Whenever you interact with people, don’t be there primarily as a function or a role, but as the field of conscious Presence. You can only lose something that you have, but you cannot lose something that you are.
—  Eckhart Tolle

(adj.) when you’re truly at peace and in touch with yourself, and nothing anyone says or does bothers you, and no negativity or drama can touch you.

Is there a name for this specific feeling?

You know what feeling really sucks that people don’t often talk about? That feeling when you’re watching someone else get something that you’ve worked for (usually way longer/harder than they have) and you don’t wanna be jealous. So you just smile for them and try to get over it. But then a lot of people keep bringing it up or you keep getting other reminders of it. Especially since most people don’t know just exactly how badly you wanted that thing. So you just sort of stand there trying to smile as realistically as possible as they say to you how great it is that this person got this. You’re just sort of standing there, aching inside trying to be the bigger person and not let it get to you. But it does, and the people don’t know that by celebrating it to you directly they’re actually making something harder on you. Wether it be your longtime crush suddenly dating someone else, or someone getting an opportunity you’ve wanted for so long. And you just have to stand there and support them and try not to be upset because that’s what good people do. That’s what you’re supposed to do.