How to be meaner and more aggressive?

So I'm a high school wrestler, I've been wrestling for 3 years now, and I'm a chill guy. The thing is, I can't be "chill" when I step on the mat to wrestle. Against my teammates, I have no problem going 150%, colliding heads, drilling heads into the ground and being relentless. However, when I have a meet or tourney, I tend to be more reserved and easy-going when wrestling. My coach tells me if I can channel the aggressiveness inside me at a real match, I am bound for the state championships. So I want to know how to get mean and learn to just pummel my opponent relentlessly for 6 minutes straight. I want him to regret stepping on the mat with me. Should I just isolate myself from the team and instead of joking and laughing, be serious and ready? Is there something I should tell myself before the match? I've also noticed if I keep myself hyped up for a match too long, I eventually crash.. So how should I, immediately before my match start, get angry and ready to destroy my opponent?.. Thanks in advance.