I believe it has everything to do with patience.
As for the oxygen tanks, my poor mother had one the last year of her life. I took her shopping many times, carting that tank along... and if she was in the way, I didn't care! She needed to get out house.
I'm like Jeanne, I imagine the person moving slower in front of me as a family member (my mother, father, sister) and have learned not to be annoyed by it.
You know what, that could be any one of us one day. You never know what life will throw your way.