Get It: Endocannabinoid production is believed to react more strongly in response to stress as opposed to pain (the stronger endorphin activator). Differentiating between physical stress and discomfort during a run is nearly impossible. Which means the same mechanism that triggers endorphins can also trigger endocannabinoids: a challenging (not killer) workout.
Raichlen says that running at 70 to 85 percent of your age-adjusted maximum heart rate is optimal in spiking the primary stress hormone cortisol, and producing endocannabinoids. (If you're 30, you'd aim for between 142 and 161 beats per minute.)
Hill's research suggests that, in small doses, mental stress may also increase endocannabinoid production. So prerace jitters could have a payoff. However, chronic stress can dull this effect.
That may be one reason why Cecilia J. Hillard, Ph.D., director of the Neuroscience Research Center at the Medical College of Wisconsin, has found that people need eight hours of sleep a night for optimal endocannabinoid production. What's more, her research shows that endocannabinoid levels are three times greater first thing in the morning compared with when you hit the hay. Though there's no scientific proof, this could suggest that a morning run is more likely to produce a high than an afternoon or evening run. Set your alarm; it's worth experimenting!
More: 7 Ways to Become a Morning Runner
Easy Bliss
You don't have to run hard to run happy. A true runner's high might be reserved for tough workouts that trigger the release of brain chemicals, but an easy run can still be blissful. There is a state of mind called "flow" or "the zone" that occurs when your brain becomes so focused on running that you aren't thinking, you're just doing. Sports psychology consultant and marathoner Cindra S. Kamphoff, Ph.D., explains how to find it.
16 Cross-Training Activities You Haven't Tried Yet
Get It:
Be Positive "The biggest threat to flow is negativity," Kamphoff says. "Runners who call the treadmill a 'dreadmill' are nearly eliminating the chance that they will find flow on it." Look forward to your run and anticipate that it will bring you pleasure.
Focus On Moving—Not Thinking Draw your attention to the feel of your footfalls, the swing of your arms, the rhythm of your breathing. "Absorb yourself in the run," she says. "By focusing on your body, you lessen internal chitchat over to-do lists and anxieties."
Cover Familiar Ground It's easier to find flow on a route where you feel comfortable and you don't have to think about maneuvering difficult terrain or finding your way.
More: 5 Reasons Running Makes You Happy
Sign up for your next 10K.