Romans 7:19-20

¹⁹ For the good that I will to do, I do not do; but the evil I will not to do, that I practice.

²⁰ Now if I do what I will not to do, it is no longer I who do it, but sin that dwells in me.

Verse 15 contrasts good desires with bad acts.

Verse 19 contrasts good desires with a failure to act.