William Burkitt on 2 Corinthians 12:10

Observe here, 1. The high and heroic pitch which St. Paul's spirit was raised to: He took pleasure in reproaches and persecutions. Pleasure is a degree beyond joy; though these sufferings were painful to the flesh, yet were they pleasing to the spirit. A Christian may not love that which he bears, yet may he love to bear: to bear, is the patience of necessity; to love to bear, is the patience of virtue: to delight to bear reproach or persecution for Christ, is expressive of the highest affection towards Christ, and lowest subjection to him, If nature suffers not a saint to take pleasure in reproaches, as such, yet grace enables him to take pleasure in what he is reproached for.

Observe, 2. The cause assigned why the apostle took such pleasure in his sufferings and abasements, because they gave him such experience of the power of Christ; insomuch that when he was most weak in himself, he was then most strong in Him. When I am weak, then am I strong; which words are a divine paradox or riddle.

The apostle affirms one contrary of another: weakness is contrary to strength; how then can a weak man be strong, when he is weak? The meaning is, That when a Christian is most sensible of his own weakness, and most diffident and distrustful of his own strength, then the power of Christ rests upon him, and he experiences divine strength coming in unto him. Christ fills none but the hungry, nor doth he strengthen any but the weak; only by going out of our strength, do we get strength; when in an humble sense of our weaknesses we rest upon Christ, the power of Christ rests upon us.