I've never done anything myself and have no plans to.
One of my best friends smoked a lot of weed for over 4+ years, that really messed with his mind and causes his family and friends a lot of worry.
He ended up spending almost 2 months in a psychiatric hospital and is now suffers from manic depression, apparently smoking as much weed as he did played a significant part in that.
However he's sorted himself out now and is now at University, I'm quite sure he regrets the past though.
Its not my place to say any more, I'm just saying even stuff like weed some people think is harmless can do a lot of damage to some people.