In F. Scott Fitzgerald's short story "Winter Dreams," there are many details which indicate that the protagonist, Dexter Green, is ambitious. At the opening of the story, we discover that Dexter's family is solidly middle class and that his father owns a moderately successful grocery store. Dexter caddies for golfers at the local country club, but only for extra money.
In the first section of the story, Dexter creates wild imaginary stories that feature him playing golf with the rich men at the country club and driving an expensive car. Later, when he leaves for college, he chooses to attend an "older and more famous university in the East"—probably Yale University—though does not have a lot of money while he is there. The story explains that Dexter "wanted not association with glittering things—he wanted the glittering things themselves." This distinction is important since it tells us that Dexter wants to be wealthy and powerful, and not just be associated with the wealthy and powerful.
As an adult, Dexter owns a string of successful laundries and makes more money than other young men. This success allows him to finally access the "glittering things" he so desires. Of course, one important example of his ambition is his pursuit of Judy Jones, the wealthy and beautiful young woman who represents all that Dexter desires. Dexter's frequent attempts to possess her through marriage constantly fail. It is no coincidence that Judy is often described as being "golden" or dressed in expensive "gold" clothing; her character is symbolic of the wealth and power that fuel Dexter's ambitions. Ultimately, though Dexter becomes incredibly wealthy, he remains unhappy and disillusioned because he cannot "own" Judy.