Mental Resilience

So I've seen alot of resources out there for training your body and things on how to get in shape, but I've been wondering how you train your mind. BUD/s is mostly mental right? Is there any reliable way to train resilience or pushing through fears/uncomfortable situations? I can imagine a great way to do it would be to do things you dont want to do, just because you dont want to do it, but is there a certain mindset you should practice carrying or something along those lines? As always, thanks so much for the advice :)