I never used to be very good at saying thank you and made myself learn the technique. For a few months I wrote the word 'Thanks' on my hand and took it with me everywhere I went. (Ruth - if that was a misrelated participle it was used for comic effect.) I have a list of people to thank on my things-to-do list and send a lot of brief postcards. They are appreciated far more than the investment of time involved in producing them.
The other week Mrs T was away on a dangerous mission with her organisation and her MD sent me a personal email saying what a good job she'd done. He appreciated it and understood what it had meant for me.
That was a nice touch. Who are the people we need to thank who are supporting in the back-ground?