Psalm 98

"Bless the Lord, my soul, and bless God's holy name.
Bless the Lord, my soul, who leads me into life. (Ps 104:1)"

Sure, its not Psalm 98, but it was the first thought I had after reading it.  This Psalm (98) is all about acknowledging the goodness of God.  You might have bad days, but God is Good, All the Time.