Kirby Blandino | Editor, The Local Aim — Decades of health and fitness R&D. What he found makes you better at every business and consumer decision you will ever make.

I took a vitamin D supplement at 125% of the recommended daily dose for months. A blood test proved it wasn't working. That one test saved me years of wasted money. That is what the scientific method does — it replaces guessing with knowing. Five steps. Works for anything.