My father-in-law turned seventy-eight recently, and during our family gathering to honor him, someone asked him, “What’s the most important thing you’ve learned in your life so far?” His answer? “Hang in there.”

Hang in there. It might be tempting to dismiss those words as simplistic. But my father-in-law wasn’t promoting blind optimism or positive thinking. He spoke those words as someone who’d endured tough things in his eight decades. His determination to press on wasn’t grounded in some vague hope that things might get better, but in Christ’s work in his life.

“Hanging in there”—the Bible calls it perseverance—isn’t possible…