Stuttering does define us. Stuttering gave us a lot of our experiences in life that make who we are today. It's a big part of who we are, especially those of us that have been stuttering since the day we started talking. Since people are suggesting what to tell him, I'm going to go at another angle and I'm sorry if this offends you. I'm just trying to suggest possible problems. Maybe it's the way you act around him when you stutter. I have friends I still stutter around cause of the way they talk to me. Are you constantly interrupting him? Are you constantly failing to let him finish his thoughts. Do you cut in after a block? The way to make a stutterer comfortable is to have a comfortable environment. Constantly telling someone it's going to be okay doesn't work, I can testify to that.