A molecule called NAD+ may hold the secret to boundless energy.  The good news: Our cells already produce it, as it helps regulate our metabolism.  The bad news: NAD+ declines as we age-by 50, levels are half of what they were at age 20.  But scientists have discovered some powerful boosters that can help cells produce more NAD+.  One of the most promising is NMN (nicotinamide mononucleotide), a form of vitamin B3 found in fruits and vegetables like avocado and broccoli.  A 2013 study showed that older mice that were given an NAD+ boosting compound containing NMN had dramatically healthier cells and muscle tissue.