What I would say to him
First off, read me bio.
I can relate.
Never make any huge, life-changing decisions, good or bad, when you are in the midst of reinventing yourself. You will think things are fine, you are strong. It will fool you sometimes. You will have great days..."This is is, this is what I want. This is the new direciton I search for." Then, it will pass. It will take time.
You will be depressed. Whatever form depression takes in you, it will come in waves as well. Revinvention is a death within you, so you must mourn. It will take longer than you think. My sports career 'officially' ended in the Fall, 2003, and I still have days, especially when you decide to stay close to once was. Then it is my theory it takes longer.
You will find your way. You have people close to you willing to support you and be there when you have your "moments." You don't always have to be strong to Livestrong.