Those who wait on the Lord shall renew their strength.
Isaiah insists that we can’t put our trust in the glory of man, at all. Because it’s a mirage in the desert. It’s a water droplet of dew that’s evaporating under the morning sunlight. It doesn’t ultimately last.
The strength we need for the Christian life is provided by God himself. Each child of God can lean into the arms of the Father, confident that he who started a good work in us will bring it to completion.