Your actions and the intentions of your heart need to match. Jesus is giving us the playbook, he is telling us the standard. The standard is perfection, either yes or no.
We are created to be in relationship with God. We run the race out of love for God himself, out of response for the love that God has given us.
Following the Lord isn't just about what we do. It is about the conversion of our hearts and letting every action flow from the choice to place God at the centre of our lives.