For me, an American, the work ethic comes from reading Benjamin Franklin's Autobiography after being inspired by a passage found in an American Literature textbook in 10th grade. [0]
edit: Of all the different philosophies a young person can subscribe to, entering in the middle of my life, I'm lucky to have chosen one of the better ones. I remember at the time really wanted to embrace an identity of being American and here is a founding father who helped draft the Declaration of Independence and signed the Constitution who was born and raised with the institution of slavery owning slaves himself and evolving into an outspoken anti-slavery advocate working to abolish the practice. That is what it means to be an American, to grow, change, and become better, just.