Henri Cartier-Bresson said this quote

To take photographs is to hold one's breath when all faculties converge in the face of fleeing reality. It is at that moment that mastering an image becomes a great physical and intellectual joy.To take photographs means to recognize—simultaneously and within a fraction of a second—both the fact itself and the rigorous organization of visually perceived forms that give it meaning. It is putting one's head, one's eye, and one's heart on the same axis.