You must be born again.
Jesus answered and said to him, “Amen, amen, I say to you, no one can see the kingdom of God without being born from above.” Nicodemus said to him, “How can a person once grown old be born again? Surely he cannot reenter his mother’s womb and be born again, can he?” Jesus answered, “Amen, amen, I say to you, no one can enter the kingdom of God without being born of water and Spirit. What is born of flesh is flesh and what is born of spirit is spirit. Do not be amazed that I told you, ‘You must be born from above.’ John 3:3-7
This is obviously not something that can be achieved by human effort. This is by the will and power of God. The Holy Spirit is the means and the evidence of this new birth. The life of the Kingdom cannot be lived through the flesh. The indwelling and filling of the Holy Spirit is the gift that keeps on giving. We must enter the Kingdom by Him and live the Kingdom life by Him. The fruit of the Spirit and one or more gifts of the Spirit will be evidence of it.