First of all, nerves before a fight are more common than not. If you find a fighter who has no fight nerves, that's a guy you should be very afraid of. Most fighters talk about it. You would do well to start reading what other fighters did to deal with their fear.
Mike Tyson famously said he felt like a wreck before every fight. It was so bad for him that he would be in tears crying. His fight trainers spent hours trying to talk him through it and calm his nerves down. The way he ultimately dealt with it was to just say, "Let's go!" when the time came. He would become angry and more focused on winning his fight and just put all of his heart into it.
The reason why you feel nerves before a fight is because your subconscious mind knows it's a dangerous situation. And it might not be dangerous in just the obvious way, but rather maybe also dangerous to your ego if you lose.
The subconscious mind is like a separate brain within your brain. It's not under your direct, conscious control. In other words, there are two of you living in your head. Both communicate with each other, but both exist more or less separate and independent of one another at the same time. It's strange when you realize how true this is.
For example, try to remember a time when you had to pee and went into a bathroom where there was something going on that prevented you from peeing. Usually it's something your subconscious perceives as dangerous. Maybe there are some nasty looking guys who look like they're on their way to a satanic ritual sacrifice. Haha. You try and try to pee, but nothing is happening. You walk away pretending that you peed, and you come back to the bathroom after those dudes leave. Now you're able to pee again. Strange, huh?
What's happening in these situations is that your subconscious mind is actually in control of your emotions and parts of your body. In the example I gave, you can only pee if your subconscious mind agrees to open up one of the sphincter muscles surrounding your urethra in order to allow the pee to start. Normally, it just seems like your conscious mind controls that, because your subconscious mind is listening to your conscious mind and agreeing to open that sphincter muscle up. But when your subconscious mind thinks the situation is dangerous, it's not going to do it. These are the times when you realize you actually aren't in direct, conscious control over much of your body. It's your subconscious that's really in control. And it can't be reasoned with!
I like to think of my subconscious mind as a little child. It gets scared or anxious easily. There are times when it thinks the situation is dangerous when it really isn't. But I can't tell it that. Instead, what I've realized over time is that I have to take that little child by the hand and gradually expose it to the danger to show it that it's actually okay.
This is known as graduated exposure therapy in Psychology. If you have a fear or anxiety that's taking control of your mind, you want to gradually expose your mind to the thing that causes it. For people who have a great deal of anxiety with regards heights, for example, that means you start by looking at a ladder from 20 feet away. Then you approach the ladder, getting closer and closer to it. That might take several days. Over time, you start to realize it's okay, so you can get closer to that ladder without the feeling of dread. Finally, you reach the ladder and touch it. That might have taken you a month to be able to do. And so on, until you've been able to climb the ladder without the feeling of dread.
The same is true about fighting. You begin with sparring lightly in an environment you're comfortable with. Nobody is really trying to hurt you, and it doesn't matter if you win or lose. Then over time, you increase the level of force and begin recording the wins and losses. You begin sparring with people from other MMA gyms. You start entering tame, low key tournaments that don't offer prize money. You're trying to approximate the conditions you'll be in once you enter a fight competition for real.
Now, maybe that does you very little good in the immediate term, because this a process that takes a lot of time. Now you know why I said in the beginning, if you ever find a fighter who doesn't have nerves before a fight, be very afraid of that guy. It's because he's been through so many fights successfully that he no longer fears them.
So that being said, the only way around your nerves in the immediate future is to try to put your mind in a hypnotic state in order to cause your subconscious mind to stop dwelling on what's about to happen, and instead, to focus on the here and now.
You can do that by doing something that requires your attention. Bounce a ball. Hit the punching bag. Skip rope. Go for a run or a walk. Listen to music. Watch a movie. Go for a swim. Solve a puzzle. Beat on some drums. Bike. Climb. Compose a poem. Do some gardening. Lift weights. Go on a trampoline. Etc. Mike Tyson said what often worked for him was having sex.
All of those things will temporarily alleviate your anxiety. Eventually it will come back when you stop doing those things. But just taking your mind off of the fight will help lower your anxiety and prevents it from worsening over time.
Good luck! Fighting is the road less traveled. But by taking that path, you can learn more about yourself than perhaps you would have otherwise. Fighting is about growing, not just about who wins and who loses.
Hope that helps.
