"Rejoice in the Lord always; again I will say, Rejoice. Let your reasonableness be known to everyone. The Lord is at hand; do not be anxious about anything, but in everything by prayer and supplication with thanksgiving let your requests be made known to God. And the peace of God, which surpasses all understanding, will guard your hearts and your minds in Christ Jesus."
Phil 4:4-7
To me, here's the long and short of it: When focused on Christ and the Gospel, Thanksgiving looking back keeps you humble. Thanksgiving looking forward keeps you hopeful. Thanksgiving in the present keeps you peaceful.
So give thanks, and for crying out loud, smile!
