The signs are there...

My oldest son is clearly beginning to have the attitude and behavior we all associate with being a teenager. He will turn 12 years old this year and is already needing to use the occasional acne treatment. Lately he wants to spend time alone in his bedroom and is very firm about wanting the door to his room closed. We are trying very hard to respect his wishes but it is hard to change habits such as walking into his room randomly. The other thing I am having a hard time adjusting to is the new moodiness he sometimes exhibits. I am not accustomed to someone stomping upstairs in response to a request to make a bed. I am trying to ignore this type of behavior because I know it is a right of passage. I just hope that this phase does not intensify greatly because I am not sure our stairs can take the stomping.