It's polite to be thankful for the kindness of strangers.
Fred, a stranger, helps Tina load some very heavy bags of dog food into the back of her car.
Tina wants to tell Fred that she doesn't need anymore help from him.
Tina thanks Fred for his help and tells him that if he hadn't been there for her, she couldn't have done it herself.
Tina tells Fred that she wishes he'd loaded the dog food into her car faster, but that he can go now.
Fred feels valued and useful and stops to help a person with a flat tire on the way home.
Fred feels unappreciated and vows not to help anymore strangers because they don't deserve it.