AS a matter of fact, God isn't asking you to be thankful. He's asking you to give thanks. There's a big difference. One response involves emotions, the other your choices, your decisions about a situation, your intent, your 'step of faith.
Joni Eareckson Tada (2010). “A Place of Healing: Wrestling with the Mysteries of Suffering, Pain, and God's Sovereignty”, p.140, David C Cook