Tell your boss what you think directly. Sincerely, everyone is willing to accept it, not too complicated.

There is nothing to be ashamed of. You are a part-time job, and the boss wants you to make money. Wouldn't it be stupid not to go to a good place? You are very kind, but the boss won't think so. Similarly, if you don't do a good job here, the boss will not hesitate to dismiss you. If the boss is a kind person, if he trusts you, he will also hope you succeed.