I have a boy also that is full off energy, he turned 3 in Jan. I had him fixed at the end of last year but he bounced back the next day like nothing happened. I had to practically hog tie him in the house to keep him from injuring himself after his neuter. It seems both my boxers have a high pain tolerance, its crazy. I just wanted to assure you that even though they are high energy they will learn with time when its appropiate to get crazy and when its not. My male knows its chill time in the house but when its time to go outside its time for him to burn about. He has always been so eager to please too, so when he did get in trouble its hard to get on to him because he takes it so bad. I dont think so much as they loose their energy level so much as mature and know what you expect of him. My female, who will be six in December, was a ball of energy until she was about 3, now she only gets crazy after a bath and when its dinner time. She is so funny. She also would get crazy playing with my male. I know having 2 dogs is alot of work, but with boxers it acually took some of the pressure off me, because there is nothing like watching 2 boxers play. I used to take my female over to friends house to play with their dogs too, and she would come back exhausted. I even babysat a friends boxer one time and I dont think they stopped playing for that 24 hours. She slept for 2 days after that.