Not all philosophies can be summarized in a catchy phrase. I ride because I enjoy it, it's healthy, I like the challenge, I like seeing the city that way, it makes me feel good, relieves stress, and because I can eat almost anything I want as a result, though knowing that I'll be facing a lot of elevation gain tomorrow is a good deterrent from consuming copious amounts of fatburgers and snickers in the first place.
I love thinking, "I bet I could ride to xxxxxxx and back tomorrow.", and then discovering I am right. I love looking at a hill and thinking, "I can do this.", and again finding that I'm right.