Honesty:
Trading introduces you to yourself and you can’t ignore it. The mentor was just being honest. He saw the guys impatience. The more emotionally the guy got about the reality of the situation the more angry the guy got. Trading is difficult because money is an imperfect feedback mechanism. The habits you create early on you may continue to pay for throughout your career even it if paid you in the beginning. The good habits you create may not pay you for awhile or you may not be able to see them paying off. It take a strong person to keep going without rewards.
Experience:
If I have learned one thing it is never to discount others experience. If someone has something to say I am smart enough to learn something from it. That does not mean that all experience are created equally efficiently. But completely discounting it is dangerous. About everything I have ever done I started off thinking I was smarter than everyone else. It started with my parents and continued to football and trading. Each step I got better. However it is important to take the information and make it work for you.