We have little power to change ourselves fundamentally, that is, to change our heart. We can be determined and resolve to change, then we slip once and are back to where we were. Say there is someone who gets stressed out all the time and you advise him not to let anything bother him, even suggesting that he abandon himself in God. It's good advice, but if the person does listen, nothing will happen. I advocate seeking union with God, precisely because this is the way to let God into your heart to let him change your heart inside out. This is how you become a new work of God.