He that trusteth in his own heart is a fool.
We sometimes think of ourselves as stronger (spiritually) than we actually are. We are basically trusting in our own heart. One clear example of this was Peter who, trusting in his own heart, vowed that he would never deny the Lord. A short time later he actually said that he never knew who Jesus was! See what happens when you trust in yourself? The Scripture says to trust in the Lord with all your heart and lean not to your own understanding. In all your ways acknowledge Him, and He shall direct your paths. This is the safe way.