Youth Sports and Mindset

 My son Gavin is seven years old and loves football. He started playing flag football at five years old and will be doing his first season of tackle football this year.  
 Just recently he attended a week long football camp where it was extremely hot (95 degrees) and he loved every minute of it. I always seem to hear negative comments from other people that it's to much for him at a young age. He also trains with me a few nights a week by working on his footwork, speed, endurance, and our sessions are usually no longer than forty five minutes. He is a very serious kid and he loves competing. Is this to much for him?
 I am trying to teach him about how to develop a winning mindset, not just in sports but in life. That you have to keep pushing through all the physical and mental pain if you want to succeed. My parents did not do anything like this with me and I wish they did. Is this to much for a seven year old?