Dear Betha, by citing this verse, you essentially appear to contradict yourself:
Ephesians 2:10:
"For we are God’s workmanship, created in Christ Jesus to do good works, which God prepared in advance as our way of life."
Therefore we need not worry whether our works are or can be "good enough", since all the works we can do were ready for us to do before we were born:
Jeremiah 1:5:
"Before I formed you in the womb I knew you, and before you were born I set you apart"
As for doing them, we have free will, but an Omnipotent God is an Omnipresent Inescapable God, as Jonah found out after spending three days and nights in a big fish, and although he was reluctant, he realized he was up against an "Irresistible God".
The scripture does not actually say that we "fall away" of our own accord, but are in fact "led away" by deceivers, which if we do and are in God's Grace, then He will bring us back as in accordance with the parable of the Prodigal Son.