Elisabeth Elliot spoke those words.

“Just do what comes next.”
Elisabeth Elliot
The resounding theme of Elliot’s life was the boundless love of Jesus, and her greatest commission was to tell others of His saving grace. This costly call led her into the Amazonian jungle of Ecuador where her husband, Jim Elliot, was one of five missionaries speared to death in 1956 while attempting to make contact with members of the Auca/Waodani tribe. Elisabeth, along with her young daughter Valerie, would later return to Auca territory to live among and minister to the people who killed her husband. Familiar with suffering, Elliot wrote, “The deepest things that I have learned in my own life have come from the deepest suffering. And out of the deepest waters and the hottest fires have come the deepest things I know about God.”
Elisabeth Elliot’s life work was to share these deepest things: the trustworthiness of God, the blessings of obedience, the hope of joy in the midst of sorrow, the call to love one’s enemy, the priceless treasure of purity, and the true meaning of Biblical womanhood and manhood. Having written over twenty books, some of her most distinguished writings include, Passion and Purity, Let Me Be a Woman, Shadow of the Almighty, Through Gates of Splendor, and The Savage My Kinsman. The latter three chronicle Elliot’s missionary work and the life and martyrdom of her husband Jim.
For thirteen years Elliot opened her daily radio program “Gateway to Joy” with these words:
You are loved with an everlasting love, that’s what the Bible says, and underneath are the everlasting arms. This is your friend, Elisabeth Elliot.
The eternal God is thy refuge, and underneath are the everlasting arms.
Deuteronomy 33:27