John 7:38" Whoever believes in me, as the Scripture has said, streams of living water will flow from within him."

Yes, vitamins and herbs can keep you healthy, but the living water within you keeps you sustained.  Because He lives, you can face tomorrow.  Because He lives, all doubt is gone.  The stream of living water in you is Jesus because you believe in His word; and when you believe in His word, you can achieve anything.