Ask HN: I hate to work with my colleague what shall I do?

My colleague is a guy that make a lot pressure and everything is bad - he has a pessimist way of see everything He looks at each opportunity to make me feel bad and make fun of me. Every meeting with him is demotivating. I am loosing my patience. I don't know what to do... I'm an easy guy who loves what he does. Don't feel like arguing with him is the solution.