From Magnum’s blog:

“Photograph because you love doing it, because you absolutely have to do it, because the chief reward is going to be the process of doing it. Other rewards — recognition, financial remuneration — come to so few and are so fleeting…there are many other easier ways to make a living in this society. Take photography on as a passion, not a career.” —Alex Webb

“Forget about the profession of being a photographer. First be a photographer and maybe the profession will come after. Don’t be in a rush to make pay your rent with your camera. Jimi Hendrix didn’t decide on the career of professional musician before he learned to play guitar. No, he loved music and created something beautiful and that THEN became a profession. Larry Towell, for instance, was not a “professional” photographer until he was already a “famous” photographer. Make the pictures you feel compelled to make and perhaps that will lead to a career. But if you try to make the career first, you will just make shitty pictures that you don’t care about.” —Christopher Anderson

“Find a subject you care about. Something that moves you. Something which stirs your rawest emotions. And then have patience.” —Mark Power

Many more here.