"People say, 'you have to have a lot of passion for what you're doing,' and it's totally true. And the reason is because it's so hard that if you don't and rational person would give up. It's really hard, and you have to do it over a sustained period of time. So if you don't love it, if you're not having fun doing it and you don't really love it, you're going to give up. And that's what happens to most people, actually. If you really look at the ones that ended up being 'successful' in the eyes of society and the ones that didn't, often times it's the ones that are successful love what they did so they could persevere when, you know, when it got really tough. And the ones that didn't love it quit. 'Cause they're sane, right? 'Cause who would want to put up with this stuff if you don't love it. So, it's a lot of hard work, and it's a lot of worrying–constantly. And if you don't love it, you're going to fail."
-Steve Jobs, 2007