The old Spiritual expresses the sentiment of determination and perseverance well: "I have decided to follow Jesus. No turning back, no turning back." (McKenzie, Preaching Proverbs, 99-100)
A woman tells of a conversation with her elderly mother, in her early nineties, still active in visiting the sick, preparing communion elements, and tutoring children at the elementary school.
"Mother," she told her, "don't you think at your age you could back off from these activities and enjoy a lighter schedule? You've earned it after all these years, and I'm afraid you're tiring yourself out."
Her mother drew herself up to her full five feet tall and answered, "When I decided to follow Jesus, I did not promise to follow him part of the way. I promised to serve him all the way. And that is what I intend to do."
I don't know what her daughter said to that. What could she say?
But I know what Paul would have said. He would have nodded in agreement and affirmation and said, "I do not consider that I have made it my own, but this one thing I do: forgetting what lies behind and straining forward to what lies ahead, I press on toward the goal for the prize of the heavenly call of God in Christ Jesus" (Philippians 3: 13,14).
David J. Williams, Paul's Metaphors: Their Context and Character
Alyce M. McKenzie, Preaching Proverbs: Wisdom for the Pulpit