Getting yourself acclimated to the feelings of uncertainty, and then doing the work anyway, i's the key to success. Making yourself uncomfortable speeds up the process of mental toughness. You have to know that it's going to be tough, you're gong to be challenged. One of my favorite storieis when it comes to exactly what you're talking about is from seal training. There are grown men who have gone their whole lives saying, i want to be a seal. And within ten to 15 minutes of being in this ice cold, 50 degree water, they will get out of the water,. They'll ring the bell and they will quit. It's all in your mind.