How Can I Tell My Kid NOT to Smoke Pot When I Do It

Now that marijuana is legal in Colorado some parents are asking themselves how they can tell their kids not to smoke it when they themselves partake.

I received an email from a listener I've known for a really long time, they are a wonderful person, hard working; church going; gives back to the community; involved with their child's school; great friend; has an amazing wife; etc. etc. not that this has ANY bearing on the story, but I'd like to point out that pot smokers are not ALL the dregs of society, they come from all walks of life.

Here's what his email said:

I borrowed my son’s car to go to the gym the other day and I found a marijuana pipe in his glove box.
I smoke pot from time to time (much less than I used to and NOT around my children), but that doesn’t mean it’s okay for him to. I’m an adult and I know how to handle it. He’s only 16.
How do I discourage him from smoking weed without feeling like a massive hypocrite?

I will leave his name off, for the obvious reasons, but do you guys have any advice for him?