Passage
Even the youths shall faint and shall tire, and the young men shall stumble and fall;
Even the youths shall faint and shall tire, and the young men shall stumble and fall;
Isaiah 40:28 Dost thou not know, hast thou not heard, that the everlasting God, Jehovah, the Creator of the ends of the earth, fainteth not nor tireth? There is no searching of his understanding.
Isaiah 40:29 He giveth power to the faint; and to him that hath no might he increaseth strength.
Isaiah 40:30 Even the youths shall faint and shall tire, and the young men shall stumble and fall;
Isaiah 40:31 but they that wait upon Jehovah shall renew [their] strength: they shall mount up with wings as eagles; they shall run, and not tire; they shall walk, and not faint.
The verse centers on "even", "youths", "shall", "faint", "tire", and "young". It is saying that the verse draws attention to "even" and "youths", so its meaning should be read from those terms before moving to application.
The nearby context moves from verse 29's "He giveth power to the faint and..." into verse 31's "but they that wait upon Jehovah shall...", so "even" and "youths" belong inside that flow. In Isaiah context, the local focus is the Holy One of Israel, judgment and restoration, the servant of the LORD, and Zion's hope.
A plain takeaway is to answer the verse's own emphasis on "even" and "youths" with trust shaped by these words, not by a vague optimism outside the passage.