Ever since I've been distance training in lieu of speed training I haven't gotten a runner's high. It's been years. When I first started running a decade ago now I used to get them all the time. It's like this second wind that comes out of shear exhaustion. I get the goose bumps as adrenalin pumps through the veins. The surge is an amazing rush lasting for about 10 minutes where everything is allllllllllllright.
I've read several articles about it before, including some that label it as a myth. Having experienced it myself, I (of course) completely disagree.
Today, I read an article about it at runnersworld.com here. According to the article:
"...you're more likely to experience runner's high when you run just a little slower than your 10-K race pace, also called tempo pace. Slow down more than that, and you don't produce enough stress. Run faster, and you get overwhelmed by the effort."
I believe the reason I haven't experienced a runner's high in so long is because I'm simply not pushing myself hard enough. Instead of running at a hard core tempo pace for a shorter time, I'm training at a "happy" fun pace for a longer time. While painful (especially in the beginning of the run), I may just have to push myself a little harder to get to that "high" place again. I think my body needs the jolt and could really benefit from both types of training. When this race is over, that is where I'll be shifting focus.