When we let go of fear, and we start to practice gratitude, we start to experience joy. There is happiness in a cup of tea on a sunny day. There is happiness in quiet meditation. There is happiness in time with friends. When we start to notice what we have, when we start to practice gratitude, we stop living in fear, and we genuinely feel happiness.
It's not happy people who are thankful. It is thankful people who are happy.