Shopify billionaire co-founder & CEO Tobi Lütke — one of the most analytically rigorous founders alive — uses affirmations. His exact words: "If you tell yourself or write down something about yourself 100 times, it writes into the neurofrontal cortex at such a deep level that your brain will start reconciling you to that. It just works." His personal example: He was terrified of public speaking. For one week he sat down every day for 10 minutes and wrote: "I love public speaking." A week later the fear was gone. "It's not like a placebo. You just actively change your neurofrontal cortex in this moment." Your brain starts shaping your behavior around the identity you rehearse most.