Well, I'm glad to make a contribution to the "learn something new everyday" campaign. I think overall the thinking part is what gets me into so much trouble to begin with, which is another reason the sex and pot make a good combo. The less I think, the more relaxed I get, the stiffer it is.
Not only longer and harder, but just a lot less stimulation is necessary to keep it rigid. It's gotten to the point I smoke a bowl, pop myself inside her and we just ever so slightly rock back and forth (different positions, similar motion). This we do about an hour and a half to two almost every day. If anyone took video of us, it'd be the most boring porn in the world, just mixed in with a dozen or so screaming orgasms (mine would be the last one).