Weaknesses of the flesh- whether they be trials, temptations, character flaws, or any other kind of mortal limitation- in and of themselves do not produce strength of spirit. In this verse, the Lord clearly teaches that weaknesses are turned to strengths only through one’s coming unto Christ in faith and humility.
Then is his grace sufficient to make such transformation. It is through the atonement of Jesus Christ that the weaknesses of the flesh resulting from the Fall are swallowed up, just as that which “is sown in corruption is raised in incorruption” (see 1 Corinthians 15:42, 53). It is not just in the next life that the “weak things” are made strong through Christ.
The Savior’s grace is sufficient even in mortality to buoy up the spirit, to strengthen and spiritually enlarge one above natural abilities. Ammon recognized this when he declared
“I know that I am nothing; as to my strength I am weak; therefore I will no boast of myself, but I will boast of my God, for in his strength I can do all things”
(Alma 26:12).
Whatever the weakness, Christ can supply the strength to overcome it. All other earthly efforts to overcome the effects of the weaknesses of the flesh, as helpful as they may be, are limited in their soul-transforming power.
It is through the grace of Christ that even mortal inadequacies are compensated for or overcome while we yet tarry in the flesh (see By Grace Are We Saved, pp. 38-39). Through faithful acceptance of the atonement of Jesus Christ all losses can be ultimately restored, all suffering can cease, and all inequities and injustices in life can be rectified. “The Savior desires to save us from our inadequacies as well as our sins,” wrote Bruce C. Hafen.
“Inadequacy is not the same as being sinful- we have far more control over the choice to sin than we may have over our innate capacity... A sense of falling short or falling down is not only natural but essential to the mortal experience. Still, after all we can do, the Atonement can fill that which is empty, straighten our bent parts, and make strong that which is weak.”
(The Broken Heart, pp. 19-20.)