Do you remember the last time somebody thanked you for something? Do you remember how you felt when it happened?
Usually, thanks is reserved for a special occasion. Perhaps you did something far beyond your call of duty, or have been outstanding over a period of time. But wouldn't it be better if we recognised these every time they happened? With just a little thank you?
Little things don't cost a lot, but can mean much. It motivates you to go out of your way to help somebody. And you may also feel compelled to thank others more often.
If everybody thanked everybody for every little thing, does the thanks then become meaningless? Perhaps. But when everybody can thank everybody (that they meet) for something, that would be a lovely world to be a part of.