Isaiah 40:29-31New International Version (NIV)
29 He gives strength to the weary
and increases the power of the weak.
30 Even youths grow tired and weary,
and young men stumble and fall;
31 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.