Holy Spirit versus Willpower

Romans 8:1-4 Therefore, there is now no condemnation for those who are in Christ Jesus, 2because through Christ Jesus the law of the Spirit of life set me free from the law of sin and death. 3For what the law was powerless to do in that it was weakened by the sinful nature, God did by sending his own Son in the likeness of sinful man to be a sin offering. And so he condemned sin in sinful man, 4in order that the righteous requirements of the law might be fully met in us, who do not live according to the sinful nature but according to the Spirit.

My friend in camp is a strong believer of the willpower of man. He believes that by sheer willpower, man can do anything he wants. Even supernatural things like the healing of illnesses, he feels that it is up to man's willpower. Ego & pride.
After doing day 19 of the Encounter! devotional, i realised how silly this school of thought is.
I am reminded that when I once brought up to my friend about his domineering nature, he told me that he is just like that, he can't change.
With willpower you can do anything? I beg to differ.
Man can't even have complete mastery over himself: his desires, his personality, his thoughts & his actions.
That's why as Christians, we cannot live on our own willpower alone, we need to entrust ourselves to the Spirit of Christ in us.

Holy Spirit, I yield to you! I live according to the Spirit, no longer bounded by the law of sin & death. Refine my thoughts, motives & actions. No longer by my own might & strength but by the Holy Spirit. The power to overcome & to conquer.

Man's greatest battle rages within him. But he will never win on his own, because he is carnal. He needs the Holy Spirit.