Proverbs 4:20-27 “Pay attention to what I say; turn your ear to my words. Do not let them out of your sight, keep them within your heart; for they are life to those who find them and health to one’s whole body. Above all else, guard your heart, for everything you do flows from it. Keep your mouth free of perversity; keep corrupt talk far from your lips. Let your eyes look straight ahead; fix your gaze directly before you. Give careful thought to the paths for your feet and be steadfast in all your ways. Do not turn to the right or the left; keep your foot from evil.”
Everything comes from our heart. Like the verse 23 says, if our heart is not right, then our whole body is affected by it. Think about it, if we have a heart that is ill, it will effect every part of our body. When we go off the path that leads us to the Lord, it can effect our whole life.