Theres a guy at my work who I want to talk to what do I say?

I work at a customer service type store, and there is a restaurant attached to it. The chefs walk though our lobby, right past my desk multiple times a day. There is this one guy in particular who is so cute and who I always talk to or smile at when he walks by, he also does the same and often initiates the conversation. I can't stop thinking about him! What should I do?