Saw an interesting piece in Nature the other day: Learning happens after DNA damage gets fixed in the brain. The "rush of electric" energy that occurs when exposed to new information, a new experience, or when trying a new skill can be so powerful that it "breaks" the brain DNA and triggers an inflammatory response. When the immune system rushes in to repair the damage, the new pattern is cemented. This is learning. An adaptation has occurred. This is memory formation.
Learning is a stressful event at all levels:
Genetic—as described above, at the cellular level memory formation requires stress and an inflammatory response.
Hormonal—Adrenaline, which is normally thought of as a stress or alertness hormone, actually helps encode learning. You learn better when adrenaline is activated.
In real live humans—You can't learn anything without getting uncomfortable. The hardest, most difficult experiences are the ones that teach you the most. My time in Outward Bound was one of the most grueling (physically and mentally) months ever, and I've always maintained that it made me who I am today. I spent my freshman year getting picked on in the locker room because I was too small for basketball or football, but it propelled me to figure out how I could excel as a track and field/cross country athlete. Learning anything is by definition going to be uncomfortable and stressful—because it's all new and you don't know how to do it yet!
This explains why the "bad" vacations—the beach days rained out, the well-laid plans gone awry—are often the most memorable, the ones we return to and laugh about as the years pass.
At all levels, above and below, learning anything is associated with stress, with discomfort, and with the adaptive response to said stress and discomfort. There's no way around this. You're going to have to get uncomfortable to learn, or even to simply form memories.
What do you think, folks? Do you agree? Can you think of any counter-examples? Let me know on Instagram. 
