Strength in Scripture is usually borrowed. “Be strong in the Lord” (Ephesians 6:10) is the pattern — not mustering your own, but drawing on His. That is why so many of these verses are addressed to people at the end of their own resources: exiles, prisoners, a shepherd boy facing a giant.

This set also holds the endurance verses — the ones about not quitting. Galatians 6:9 promises a harvest to those who do not give up doing good; Hebrews 12:1 pictures the whole life of faith as a race run with weights deliberately dropped.

Read Philippians 4:13 carefully: in context it is about contentment in want and plenty alike, not athletic achievement. The strength on offer is for enduring your actual circumstances, whatever they are.