You're too pessimistic.
I disagree with your pessimism.
I have lost hope for the result. （not hopeful about）
I don't want to be infected with your pessimism.
A: George, you're about to play, do you have cold feet?
B: To be honest, I'm not nervous because I'm not very hopeful about the game.
A: Why do you say so? I've never heard you say such pessimistic words.
B: I say for a reason. The player against me is much stronger than I, and I'm really not confident getting the better of him.
A: Come on, how can you grow the aspirations of others to outdo yourself. Didn't you beat someone stronger than you before?
B: It's different this time. I'm facing with the boxer called Tyson. So far, he hasn't lost all the cumulative competitions. Isn't it horrible?
A: So what? You have your own strengths. As long as you give the flexible advantages into the play, I'm sure you can make it.
B: My advantage can hardly stand a fight before him.
A: Your idea is too pessimistic. Clear it up quickly.