The stranger who let you go ahead with your two items gave you three minutes and a better mood. Pass it on.

Small courtesies are transfers of time. Someone with a full cart decides your three minutes matter more than their three minutes, and they will never find out whether it helped. What you get is two things: the minutes, and the reminder that strangers sometimes act in your favor for no reason. The second lasts longer than the first.

Watch for your turn on the other side of it. Next time you are in line with a load and the person behind you has a drink and a candy bar, wave them forward. Hold a door, give up the better seat, let the car merge, and none of it needs announcing.