2 Corinthians 12:10 (Weak, but still Powerful)

Greek: διὸ εὐδοκῶ ἐν ἀσθενείαις, ἐν ὕβρεσιν, ἐν ἀνάγκαις, ἐν διωγμοῖς καὶ στενοχωρίαις, ὑπὲρ Χριστοῦ· ὅταν γὰρ ἀσθενῶ, τότε δυνατός εἰμι.

ESV: "For the sake of Christ, then, I am content with weaknesses, insults, hardships, persecutions, and calamities; for when I am weak, then I am strong."

NWT 2013: "So I take pleasure in weaknesses, in insults, in times of need, in persecutions and difficulties, for Christ. For when I am weak, then I am powerful."

David E. Garland, 2 Corinthians, 882-3 of the electronic edition:

Paul scores his point with a memorable aphorism, “when I am weak,  then I am powerful,” which is the key for interpreting all that he says in this section. The point is the same as in 4:7. The power working in Paul is most clearly seen as coming from God when he appears to be weak. “I delight in” means that he accepts the way Christ's power works in his life through his weaknesses. That does not mean that he does not groan under the load of suffering (5:2, 4) and long for the mortal to be swallowed up by life (5:4). But he knows that his suffering follows the precedent of Christ's suffering. It was something that God enables him to endure, not escape. What he endures, he endures for the sake of Christ, and the paradox of the power of God hidden in his apparent weakness parallels Christ's weakness and power  demonstrated in the crucifixion. Leivestad rightly sees, “As the power of God was revealed through the weaknesses of the crucified Lord for the salvation of  the world, so the life and power of the risen Christ are being revealed through  his weak apostles in the midst of humiliations and afflictions.”⁴⁴¹ The false apostles keep the Corinthians from seeing how Christ's power is at work in him and lead them away from the cross of Christ. Paul's goal is not simply to defend himself, but to help them “see things correctly” through the proper spiritual lens.⁴⁴² 

Paul concludes with a brief summary of the hardship lists in the letter. He “delights in”(the word eudoke can also mean “is pleased”) with his “weaknesses, insults, catastrophes, persecutions, and pressures.” If en hybresin is to  be interpreted as “with insults” rather than “with mistreatments” (see 1 Thess  2:2), Paul may have added it because of the rivals' insolent slander against  him as one who was weak, debased, and amateurish. “Catastrophes” refer to  the “hardships” he has listed in 4:8–9; 6:4–5; 11:27–28. The “persecutions” are  listed in 11:24–25a, and the “pressures” or difficulties (tight situations) are  listed in 11:25b–26. The phrase hyper Christou (“for the sake of Christ”) is interpreted by the NIV (RSV, REB) as connected to the phrase, “I delight in.” Paul placed it at the end of the lists of hardships, however; so it is better to connect it to the weaknesses, insults, hardships, persecutions, and calamities for the sake of Christ (NRSV). This means that he is not pleased with them for Christ's sake but endures them for Christ's sake.