Huh. This would certainly explain a lot. I can't get high from cannabis, and I've never ever gotten a runner's high despite doing a weekly 6 mile run for the past 3 years and training hard for boxing.
Mostly running is just a mix of pain and boredom for me to the point where I simply cannot bear it. The only way I can run is if there is a goal/agenda of some sort...like playing Soccer for instance.
Exercise also tends to increase my appetite, especially when lifting weights. I wonder if this is related to the endocannabinoids.
Also, what do you mean you can't get high from cannabis?
Running itself is pretty damn boring, which makes it hard to do it for more than an hour. It is nice to get outside, though.