As appealing as drugs and alcohol can be, I think that there is no greater pleasure than the feeling you get post-run. As someone with a relatively addictive personality, I have found that running is easily one of the best feelings in the world.
It may sound ironic, but the true joy of running is found in the suffering. Many people who have not joined the cult of runners will not understand. There is no greater feeling than sprinting up a steep hill in 90 degree weather while listening to Green Day. I find that the more deranged and aggressive I feel, the more I am able to push myself. If you happen to find yourself in the middle of Wyoming, as I have, mid-run and exhausted by the dry heat, it will probably seem within reason to stop. However, in these intense states our bodies go into overdrive and through sheer panic we are able to find extreme amounts of energy, even in near exhaustion.
Your true state of exhaustion is far beyond what you think it is. The limit does not exist, that is until you literally collapse on the ground, post-adrenaline rush. When we start thinking of running, not as a passive 20 minute jog on a treadmill, but an opportunity to battle ourselves, the act of stopping becomes akin to giving in to our own weakness. I have come to think fairly melodramatically about running. There is something rather sacred about collapsing on top of a hill out of pure exhaustion. I have found that running has made me a better person. My love of suffering, both mentally and physically has allowed me to push past pain and into something greater.
So, instead of dissociating on the internet, I would highly recommend a nice sprint in the rain.