I think the best tool for regulating emotions (fear, anxiety (which is closer to excitement), excitement, anger, etc..) would be mindfulness meditation/awareness.
A lot of it is perspective, but it takes practice to be aware of when emotions arise up.
This is a big thing for 99% (hyperbolizing a bit here) of people who struggle with what they call mental game. Perspective is a big thing. It's also a simple thing.