That response is first the act of faith, which is an act of both reason and will, and then the act of love and self-surrender which follows faith, and then the continuous acts of communion and consecration.
All must commence with recognition of His free gift of Himself to us in Christ. We come empty-handed. That gift recognised and accepted moves us to give ourselves to Him. When we give ourselves to Him we find that we possess Him.
Further, there must be continuous communion. This mutual possession depends on our occupation of mind and heart with Him. We possess Him and are possessed by Him, when our wills are kept in harmony with, and submission to, Him, when our thoughts are occupied with Him and His truth, when our affections rest in Him, when our desires go out to Him, when our hopes are centred in Him, when our practical life is devoted to Him.