We should praise and give glory to God for every blessing in our lives because everything good comes from God. He alone is the author of all beauty and goodness (Genesis 1:31). The sin within us taints everything our minds conceive and our hands create. Therefore, any good that comes out of our lives is because God chose to perfect our imperfections and to purify that which is unclean.
We could never do that on our own. We could spend our entire lives striving to be good and never achieve it for a second. Things we do might appear to be good, but under the covers, we are still as imperfect and sinful as always. There is no goodness apart from Christ.