In this short Flex Diet Podcast episode, I share a reminder that the PhysFlex Surge enrollment closes Monday, April 27, 2026 at midnight PST, and I give more context on what’s inside the PhysFlex Certification. I explain how Level 1 (Flex Diet Cert) covers nutrition and recovery basics, while Level 2 (Physiologic Flexibility) focuses on becoming more robust and resilient by improving the four pillars of homeostatic regulation: temperature, pH, fuels (including ketones), and air (managing oxygen and CO2).  I walk through my eustress vs distress model, why most interventions work better with lower intensity and higher frequency, and how misapplying tools like cold immersion, sauna, or breathing methods can backfire without the right context. Episode Sponsor: Physiologic Flexibility Certification: https://physiologic.miketnelson.com/sales Available now: Grab a copy of the Triphasic Training II book I co-wrote with Cal Deitz here. Episode Chapters: 00:17 PhysFlex Surge Deadline 01:10 Who the Cert Is For 01:55 Four Pillars Overview 02:31 Time Cost and Zone 2 03:16 Sauna and Cold Progression 04:16 Eustress Versus Distress 05:01 Training Frequency Principles 07:43 Course Structure Breakdown 08:30 Research Meets Application 09:29 Context Matters Example 12:32 When Interventions Backfire 14:29 Wrap Up and Reminder 15:12 Medical Disclaimer Get In Touch with Dr Mike: Instagram: https://www.instagram.com/drmiketnelson/ YouTube: https://www.youtube.com/@flexdietcert Email: Miketnelson.com/contact-us