Today I had my first game of the season. We lost, but we didn't lost because we had less level than the other team, the first set we won. My teammates have a weak mentality, when they miss a few points they start being depressed and they don't play well, many of our games are lost by this problem. I'm the captain of the team and when this situation happens I try to cheer my teammates and I try everything but I can't solve the problem. What I should say to them? I'm very annoyed but I can't solve it, I need help :(