If you always host Thanksgiving dinner, pick up a blank journal and a pen and start a new gratitude tradition this year. As people are waiting for dinner or digesting their big meal afterward, pass the journal around so they can record what they're grateful for. They don't have to write a lot, just a few lines to mark what has mattered to them most this year.
Then put the journal away with your Thanksgiving decorations and get it out the next year. Over time, it will become a record of what your family is grateful for.
Quick Tip
I do this with my family, and they always pretend to hate it when the journal makes an appearance. The thing is, I regularly see them flipping back through the past years' entries to see what was important to them (and everyone else) in the past. This is one of our favorite family traditions.