Re: Mental Toughness
One of my teachers used to say:
"Never, never, never give up! But do change how and what it is you're doing, especially if you're not getting anywhere."
I think if something isn't working then, try it another way, or another day. Work on something that you're better at for a bit to re-establish your confidence, and then look for ways to transfer some aspect of what you can do (or what you are comfortable with) to those things that are more difficult or challenging for you.
Breathing also helps a lot with all things that are difficult - if you focus on your breathing then less of your attention is available to focus on whatever it is that is intimidating you or causing you discomfort.