“He gives strength to the weary 
    and increases the power of the weak.

Even youths grow tired and weary, 
    and young men stumble and fall;

but those who hope in the LORD 
    will renew their strength. 
    They will soar on wings like eagles; 
    they will run and not grow weary, 
    they will walk and not be faint.”

Isaiah 40:29-31 (NIV)