The hardest part of a workout often comes during the 20 minutes leading up to your actual routine, when you change your mind about 15 times, and come up with 15 reasons for why you don't want to sweat, before forcing yourself to finally do it (probably because you'll get charged for that missed class if you do bail). Once you're actually in the midst of working up a sweat, though, it tends to feel pretty good. Of course, you probably already know about the magic of endorphins, but the science behind why working out makes you happy is a little more complicated than that.
People usually describe the positive effects of a workout on your mood in the context of your body's release of endorphins during exercise, but that doesn't actually paint the whole picture. When you work out, your body first recognizes this physical activity as a type of stress, which leads to the fight-or-flight reflex, an evolutionary response that your body has in the face of danger, according to Harvard Health. At this point, two things happen: Your brain releases endorphins, which are meant to fight the feelings of stress, as well as a protein called BDNF, which is meant to protect your brain from that stress, as well.
Believe it or not, endorphins can have an addictive effect on your brain, as the hormones are chemically similar to the kind that morphine creates.
According to a 2010 study published in the Hawai'i Medical Journal, endorphins are somewhat similar to morphine in terms of the effects that each can have on your brain, in that both can activate certain neural receptors that ultimately minimize any discomfort your body might be feeling. The difference, of course, is that endorphins definitely provide a much healthier high to pursue.
The key to all of this, though, is the relationship between stress and endorphins. According to the Daily Burn, you only get that euphoric release of happy hormones if your body is under enough stress to alarm your brain — which is why a nice, long walk with your mom probably won't make you feel on top of the world, at least not in the same way a series of sprint intervals might.
But there are still benefits to those more low-key workouts, if you're not really into the super intense stuff. Case in point: Research done by the National Institute of Mental Health revealed that non-stressful exercise (like going on walks) might not lead to that massive, fantastic rush of endorphins, but it can still contribute to a decrease in daily stress, if you keep it up over time. However, the study in question involved mice, not humans, so the connection is obviously still in preliminary stages.
But it's not just endorphins that are making you feel so dang happy during a workout.
CNN reports that, when you're working out, your brain also increases the production of neurotransmitters like serotonin and norepinephrine, both of which work to send messages of well-being and happiness throughout your nervous system. Between the endorphins and these neurotransmitters, exercise basically causes your brain to work on overdrive to reinforce feelings of positivity and happiness.
But before you start scheduling in a two-hour workout each day to hoard up as many of these good vibes as possible, take a mental check: Too much exercise can be a bad thing for your mood, according to LIVESTRONG, and Psychology Today reports that it might even be bad for your mental health.
Working out for more than seven and a half hours each week can make you feel worse, rather than better, according to a 2012 study led by researchers from Columbia University.
If you're feeling kind of bummed after a workout, it might just be because you're overdoing it. Like many things in life, exercise should be done in moderation, and in direct consideration to how it's affecting your physical, mental, and emotional health.
Working out for 30 to 45 minutes a day is an easy baseline to work with, if you're shooting for all of the benefits that exercise can provide. Happy sweating!