Instead of saying, "I can't do this", think to yourself "How can I find a way to accomplish this?"
Instead of saying, "I am stupid", change your mindset to "I can learn."
Instead of saying, "I made a mistake", change your thoughts to "I can learn from this mistakes."
Instead of saying, "Someone will always be better than me", say "How can I become the best me that I can be?"
Instead of saying, "This is too hard", tell yourself "If I put in more time and effort, I can do it."
Instead of saying, "I quit", try to say "I can definitely find a way around this."
Instead of saying, "My day is ruined", say out-loud "Is my day actually ruined or did I make that small thing a much bigger deal than it should be?"