Isaiah 40:8 (NKJV)
The grass withers, the flower fades, but the word of our God stands forever.
The Lord says in verse six "All flesh is grass" and then says it won't last. Life is frail and short. About the time we get warmed up we wear out. Is that what life is all about? The word of God is forever. There is a solution to our frailty in the forever true word of God. It is found in a verse at the end of this chapter:
Isaiah 40:31 (NKJV)
But those who wait on the Lord Shall renew their strength; they shall mount up with wings like eagles, they shall run and not be weary, they shall walk and not faint.
Instead of wearing ourselves out, here from the word of the Lord, which is forever, is a promise of renewal to the one who waits on the Lord. This is a supernatural strength of endurance for waiting upon (service to) the Lord.
What a great promise! I figure my flying and running days are over, so I'll be happy with the walking and not fainting part. But who am I to suggest how God will empower me? Waiting on Him...