How to use adrenaline in Martial Arts?

I have a question to ask. How do you use adrenaline in Martial Arts? How do you control it to your advantage. I ask this because I was once in a belt test for Judo. I was nervous and I really wanted that belt. Instead of executing my throws like I normally did, adrenaline coursed through me and I went wild. My throws were unbalanced, my groundwork was terrible and I couldn't even execute Osoto-gari one of the simplest moves. Because of this I almost failed my belt test. I want to do better next time so please help!