The most important aspect of any training is the brain. It’s your most effective and questionable muscle.
You’ll see guys in the gym about to bench say, they start breathing heavy, keep readjusting the grip. Fighters, actually superior but take a few shot and start to question themselves. Runners, about halfway through a race or hikers on a climb, the brain is what makes you keep going. Not insults. Needs to come from you and your will. Set your brain and do it