12 Therefore, brothers and sisters, we have an obligation—but it is not to the flesh, to live according to it.

Read Romans 8:12 Using Other Translations

Therefore, brethren, we are debtors, not to the flesh, to live after the flesh.
So then, brothers, we are debtors, not to the flesh, to live according to the flesh.
Therefore, dear brothers and sisters, you have no obligation to do what your sinful nature urges you to do.