In Colin Powell's book My American Journey he talks about a job he had as a janitor when he was a kid. His supervisor told him when he started that if he did poorly because he felt it was beneath him everyone would think "well, that guy isn't even good enough to be a janitor," but that if he excelled then people might notice and think "this guy is great, we should see what else he can do."
I'm paraphrasing because I don't have the book in front of me, but I never forgot that part of the book - do your best at whatever you are tasked with and show how good you can be by doing a superior job and opportunities will follow.