My son was 2 years old when he got his first pair of eyeglasses. At first he resisted wearing them until he realized he could see properly for the first time in his life.
A few days into wearing his glasses, I brought home a 5 pound bag of individually wrapped chocolates that I was planning on taking to the office in a few days. He had gone upstairs to his toyroom and he was being way too quiet for too long. I went up there and he was surrounded by wrappers, covered in chocolate. Half the bag was gone, and he was so proud of himself: "Mommy, I not need help to open them, so I not had to ask!" It was the first time he had been able to see where to pull to open the wrappers. I was so happy that he could finally see that I couldn't be angry.
I had to tell him that he still needed to ask permission to take the candy, even if he didn't need help opening it anymore. The punishment was his bellyache. Kid's lactose intolerant.