Jonathan Haidt on the Age of Outrage. Long, but worth reading in its entirety.
Eliud Ngetich does a fartlek workout in Central Park in NYC. Like a bullet train speeding by cars stuck in second gear.
The same workout in Eldoret, Kenya.
Slate Star Codex on the risks associated with Adderall. I was on Concerta, which is essentially time release Ritalin, from 2006-2010. I developed a tolerance for it where I basically stopped noticing its effects. But, despite the tolerance I had acquired, I also noticed once I had started getting back into semi-serious running that it was causing me to have an elevated heart rate, about ten beats a minute higher than it would have been otherwise. That was compelling enough to make me give it up.