Examine yourself, down to the very "core" of you. Are you perfect? Have you tried to do everything good- give selflessly, give up "wrong desires" or behaviours? Do you always be kind, never thinking any bad thought towards anyone? Never tell lies, never been mean to anyone ever?
When we face the truth about ourselves, and see that we can't ever perfect ourselves, by giving up earthly things, by suffering, by rituals...and we learn that God send Jesus, to pay the price, to take our place for any wrong we have done- and we admit and humble ourselves and say yes we need a Saviour..
Then God sends you His Spirit to dwell in you. God does all the transforming of you from the inside out. God indwells you. You receive eternal spiritual life from that moment.
You have a new "you" inside- which is the Holy Spirit. God changes you, you just submit to the Holy Spirit in you and follow Him. You will want to- naturally when you have Him. Your desires change. You then go about your life, letting God lead you, and be light and life and love in the world, to all you live with and meet.
It is all of God. You just say YES I need a Saviour, and realize God provided one- Jesus Christ.