... I just don’t want to fail you know? A lot of it might come down to mental strength but maybe I can be a little more prepared than your typical UZ contract marine
Focusing on failure will cause you to fail, focusing on the next 30 seconds will get you through any selection course in the military.
Did you read the threads I sent you to in the pm? If not, get on it, they'll answer 95% of any questions you have. You will NOT be spoonfed info or advice during your selections, no matter your rank you are expected to act as an NCO or staff officer during that time - innovation, knowing the rules, teamwork, self reliance and fortitude. If you quit, it's on you; if you succeed, it's on you. There is no magic bullet, it's about accurate shot placement.