vanth the very first time i had sex i knew exactly what i was doing (this was before i ever took any drugs or smoked ciggies) because i was healthy back then (and watched a fair bit of p0rn too LOL).
i remember that session lasted 2 1/2 hours which compared to my sessions these days... was pretty banging haha
so in closing, don't smoke if you can help it... because you'll lose your f#kng stamina! :D