Compare and contrast how Tolkien presents Bilbo's ambition in the opening and mid-section of the Hobbit?

At the beginning of the book, Bilbo is satisfied with his Hobbit hole and Hobbit-life. He cares nothing for excitement or adventure beyond his hobbit village. He enjoys six meals a day and the contentment of the familiar. Bilbo becomes more ambitious and resilient as the adventure moves forward. He takes his role of "thief" more seriously. He is determined to face the dangers ahead of him which includes the great dragon Smaug.