I fully believe in looking at the glass half-full, but sometimes, it's a little crazy. People live ridiculously optimistic and I feel like you could keep getting disappointed. But, I'm also a firm believer in not being too negative.
Yes, you're really not pumped for that exam you have to write, but is worrying about how you're going to FAIL really going to help you? I'm not saying be blind to your situation, but at least have hope. Never give up on yourself.