After I read THIS article everything made a little more sense to me. When do you feel most grateful in your life? For me, it usually tends to be around the holidays when I am sharing so much love w/ friends and family at different seasonal events (and also in the summer when the sun is out, and the ice cream is plentiful.) If you can adapt and attitude of gratitude all year round ( not JUST at Thanksgiving) then you will find yourself in a better place where you feel content and happy.
It's not easy, but with a little bit of practice you will notice a difference.