The word Paul uses for gentleness (prautes) is the same word Matthew uses for the beatitude: Blessed are the meek (or gentle or humble in heart). Jesus spoke of himself in that way, that he is gentle and humble of heart. He invites us to take his yoke on us because he is so gentle he will never "break the bruised reed" (Is 42:3).
Jesus promised he would send us the Spirit. Of course he has already sent the Spirit, but he can do that again and again. As time goes on we can grow in our capacity to receive the Holy Spirit.
Do I turn to Jesus with trust?
Prayer to the Holy Spirit
Holy Spirit, Lord and Giver of life, you who came down upon the apostles in a mighty wind and with fire, who filled the house where they were and gave them the gift of tongues to proclaim the wonders of God, come down now upon me as well.
Fill me with yourself and make of me a temple wherein you dwell. Open my lips to proclaim your praise, to ask your guidance, and to declare your love.
Holy Light, divine Fire, eternal Might, enlighten my mind to know you, inflame my heart to love and, strengthen my will to seek and find you. Be fore me the living and life giving Breath of God, the very air I breathe, and the only sky in which my spirit soars. Amen.
Below is another version of the Taize chant of the Veni Sancte Spiritus.