"I will bless the LORD at all times; His praise shall continually be in my mouth."
David's intentions (above) were good, and he was sincere in his profession; but the truth is that we do not always *consciously* "bless the LORD," (though we should). It is not that David is lying, or misleading anyone, because God has so orchestrated the lives of His redeemed churchmen that *in fact* they *do* praise and bless God with all that they do--whether they realize it, or not.
Even when regenerate people sin--which happens a lot--they are *blessing* God by the fact that those sins are forgiven, and by the inevitable resulting repentance that follows. Let us resolve to always praise God, because this is good; but let us recognize that it will sometimes take less-than-obvious forms.
[Puritan quote of the day: "Praise God for every smile, and rejoice in the least." --William Bridge, in "A Lifting Up for the Downcast"]