Tips for Teaching Gratitude to Little Ones?

I’m trying to teach my 3-year-old about gratitude, but not sure where to start? He’s at that age where “thank you” seems more like a chore, and I get it, he’s still so little! But I’d love to start planting the seed of appreciation now.
We talk about sharing and being kind, but gratitude seems a bit harder to explain. Has anyone tried activities, books, or even games that worked well for teaching their kids about being grateful? Would love to hear what worked (or didn’t) for you all. :blush:
Thanks in advance!