I'm always surprised that more people don't do this. It will be a hot sunny day, and I'll see people standing at an intersection waiting to cross. They'll be out in the sun, when mere feet away are shady spots they could wait in. I don't understand how/why they tolerate the heat instead of expending the tiniest effort to get in the shade.

I did that as a teenager, because I had stable routes (to/from school at roughly the same times). As an adult, I maintain awareness of the sun's position and keep following/avoiding the shadows on hot/cold days, sometimes crossing the street back and forth or in advance of a shade I'd like to take/avoid.

It's almost an automatic process, but it has a visual perception component - on hot days, the lit side looks "too bright" to me, and on cold days, the shaded side looks "too dark" - so I take the side that looks "just right".