Last Tuesday at seven in the evening, I laced up for my usual neighborhood loop and made it exactly four blocks before I noticed the streetlights flickering on above me. Two months ago, that same run happened under a sky so bright I wore sunglasses. Now I was squinting at cracked sidewalks and dodging shadows I couldn’t quite judge. My training partner laughed when I grumbled about it, but my coaching brain was already doing the math: we are entering the six-week stretch where daylight disappears at roughly two minutes per day, and most people don’t adapt until their routine…