It is not enough to merely know what to do; we must also have the power to do it. Left to our own strength, we would never be able to obey God.
Thats why at the end of the book of Hebrews, the author prays for God to work in his readers what is pleasing in His sight (Hebrews 13:20-21). The author knew that all the exhortations of chapters 1-13 were insufficient without the enabling power of God.
We (I) must begin to learn that everything we do for God is a gift from God.
If you want to chew on this more, you can listen to my Easter Sunday sermon.