Psalm 106:1 Praise ye the Lord. O give thanks unto the Lord, for He is good, and His mercy endures forever.
Our response to the Lord’s goodness and everlasting mercy is praise and thanksgiving. We can praise the Lord and thank Him at all times, in good times and and in bad times, because the Lord is always good and His strong mercy lasts forever. When we see, hear, and feel the goodness and mercy of God in the Gospel we naturally praise the Lord. But He is still good, kind, forgiving, and merciful all the time whether we feel it or not. So we thank Him always, no matter the present circumstances.
When we don’t feel thankful, we thank Him anyway, for our feelings don’t affect His goodness and mercy. But by faith we praise the Lord and the result is that we feel better. Because God is always good, we can be always thankful. The gospel comes first, then follows faith, then follows feelings. Praise in the spirit and thankfulness in the heart brings pleasant emotions with it. Believe the gospel, respond with praise, enjoy a sense of wellbeing.