Isaiah 40:29-31

The promise is for people who have run out: “the faint” are the exhausted, and those that “have no might” have nothing left. To “wait upon the Lord” is not idle waiting but hopeful dependence, looking to God and leaning on him. Such people “renew their strength”, or as the word can suggest, exchange their strength for a new supply. The images then come down to earth: soaring like eagles, then running, then simply walking without fainting. The last is perhaps the most precious, because most of life is walking.

Isaiah 40 opens a new part of the book, addressed to a people who felt forgotten. Many scholars connect chapters 40–55 with the Jewish exiles in Babylon; tradition reads the whole book under the name of the prophet Isaiah. Just before these verses the people complain, “My way is hid from the Lord”, as if God had stopped noticing. The answer points to the stars, each called by name, and to a Creator who “fainteth not, neither is weary”. The tireless God gives strength to the tired.

Runners, caregivers, students, people with long illnesses and those simply worn down all find themselves here. It is worth noticing what the passage admits: even the young and strong “shall faint and be weary”. So the verse is not a promise never to be tired, and it is not a medical promise. Tiredness is not a sign of weak faith. The hope is that strength can be received again, day by day, from someone who does not run out.

Compare 2 Corinthians 4:16 and Matthew 11:28.