When we find ourselves in difficult situations, we also find ourselves doing things that we never knew we could. We become better, stronger, smarter, more creative people when we have to. There have been many times in my life when I have done things that I didn't previously think I could. Some of these things you just do, and others you have to work your way up to but, one way or another, being placed in a situation which asks more of you than you thought you were able to give allows you to find parts of yourself you didn't know were there. You find a way to do what needs to be done, whether through brute strength, sheer force of will, creative thinking, or whatever, and you do this simply because you must; because it's necessary.
Why though, do we have to save the best parts of ourselves for times when we absolutely have to use them? The truth is, we don't. We can all choose what is most important to us, and live as if those important things are matters of life and death (and sometimes they really are). We can force ourselves to be our best by simply deciding that we have no other option.
When you talk about animal rights and veganism with the average person, you get lots of responses like "I could never do that!" or "I could never live with (insert random animal product here)." The truth is, yes you can! We all can. It can be difficult, especially at first, but we are strong. We are so much stronger than we realize, and the only thing we have to do to bring out that strength is to decide that we have to. I think that's the real difference between vegans and other people. It's not the we're stronger, or that we don't like those foods as much as other people do, most of the time it's not even that we care more. It's just that we decided that veganism is necessary. Once you've done that, the rest is easy.
Basically, necessity = Eve (from Supernatural).