It got me thinking: I had the freedom to turn around any time I wanted. I felt the desire to turn around somewhere between the start and end of the street. But I ended up walking to an end of the street as marked by a street sign. It felt better, mentally, to stop at a preexisting stopping point/boundary than to do it somewhere where a point/boundary wasn't marked out. Human tendency towards order, I suppose (aside from those of us who choose chaos). Neat little quirk of human brains.

We get endorphins from completing tasks we set.

(Dopamine? Now I'm not sure which)

Dopamine is the reward one.

Endorphins are stress relief, serotonin is stability, oxytocin is your mooshy feels.

Maybe it's a similar effect to OCD, except not compulsive or a disorder, when you get stress relief from completing some arbitrary task like that.

Stopping at some pre-defined point also let's you offload the mental task of figuring out where to stop, and any possible guilt of stopping "too early". If you chose a spot to turn around in the middle, it would be someplace that you chose to turn around. Could you have gone further? Was that the best spot? Etc

Reaching the end of the street, it's more of "oh, well, this is where the street ends anyway, guess this is where I turn around".