Tips for developing mental toughness. . .

I don't know if mental toughness is the correct term. Twelve YO DD pitches well in practice and in warm-up, but come gametime, she has trouble. I'm pretty sure she is "trying too hard" to pitch strikes, which slows down her body and completely messes with her form and as a result, her pitches. This is a recent development. Any tips to help her drown out the noise and disregard the pressure, so she can just do what she knows how to do?

In my DD's case she was an overthinker at the mound. Which resulted in a lack of overall focus/confidence. I tried many many things over the years including the full assortment of books to read. What was the "secret-sauce" in the end for her => plain ole hard work under the direction of a military-like Juco head coach that mentally challenged and pushed her like no other.

She came out of that Juco year like a totally new competitor. She was also in the physical condition like she never was before. In Juco playoffs, in the circle, she was General Patton. I was nothing short of shocked by her mental transformation.

As an older parent and basically empty-nest I look back and if I had to do it all over again I would strive to find an experience for my developing children to be more personally challenged. Like taking a summer to go to a military boot camp type experience. I look at my 3 kids and my DD with the one really challenging year and my one boy with his Marines training and they are mentally on another level with their confidence due to those physical/mental challenges.