There are many ways to show your thanks but we were taught that we should say it, weren't we? Do you remember being told that the "magic" words are please and thank you?
After EVERYTHING that's done for us, we could send an email, make a phone call, mail a "thank you" card, send flowers, do something special that the other person likes (and that you know they do) or send an electronic card that makes them smile.
Say thank you all the time and know that very few others do!
Here's another good side effect of this. You get remembered. You get cheques faster, things done for you with a smile and immediately, repeat and referral business and best of all you feel good.
What have you done today?