He gives power to the faint and weary, and to him who has no might He increases strength [causing it to multiply and making it to abound].

Even youths shall faint and be weary, and [selected] young men shall feebly stumble and fall exhausted;

But those who wait for the Lord [who expect, look for, and hope in Him] shall change and renew their strength and power; they shall lift their wings and mount up [close to God] as eagles [mount up to the sun]; they shall run and not be weary, they shall walk and not faint or become tired. (Isaiah 40:29-31 AMP)