Greeting Richard,
I used the diving to help me to encourage me to live a healthy life style.
I loved to smoke, have a few or more drinks, eat crazy, etc. you get the idea! Just a normal guy!
What I discovered was that I loved SCUBA more!
The experience with your son will change your life my friend!
Take the time to make sure you two grow together!
That is all the reason you need!
Hang in there when it gets tough, drink water like crazy, walk / run, exercise sweat it out!
You can do it, when your skin crawls, you can taste a smoke, and you get that crazy twitch just keep walking.
It gets better, easier every time you deny the urge!
It is mind over body, YOU ARE THE MASTER OF YOURS!
CamG