Buidling mental toughness is one of the key things that separates good crossfiters from good great crossfiters.

If you are talking to your self during a WOD chances are its negative talk, if you can just totally focus on each repetition and performing that rep to your best you will perform much better.
Imagine this:
You are performing a tough wod with someone you know will beat you, however you are close to their fitness level. Also you are not sure of how best to perform this workout? will you burn out?
During the wod:
Your mind will be already saying don’t let them beat me too much, don’t burn out, come on your beater than this ect..
Now imagine your mentally stronger
Your performing this wod with someone, you are confident you will win, you are unconcerned by what they are doing. You are focused on each rep and aren’t even concerned by how your legs feel or how many reps you have left to do, just optimising each rep.
How do you think you will perform in each of these examples?
Is obvious, the first example has too much going on in his head to truly focus. He also has too much negative chat and will panic when he even sees any sign of fatigue. The other is fluid efficient and focused and will smash this wod.
So how do you develop mental toughness?
Thats easy, the mind is simple. You can do it instantly, however it is likely you have enforced a lot of bad habits during workouts.
So you need to develop your mental capacity to focus on each rep and feel calm.
Ill keep this simple for now and expand later on, but the first step is:
Be calm before your wod, focus on 5-10 slow breaths.
Now in each wod be positive and build this ability to focus.
With each workout you will now build on this focus and positive approach.
I also recommend a short positive phrase you will use before and during the workout.
Like Matt Braids “Now, for me, I focus on head down, mouth shut, mentally tough and physically dominant.”
Check out his article on how he deals with this:
Crossfit mental toughness article