While Kyle is out of town, The Back of the Pack Podcast hands the mic to one of our favorite guest hosts — Karin Velez from the Just Grow Something Podcast. This week, Karin brings her science-based expertise and Marine Corps mindset to explore the power of novel stimulus in your running routine. She explains how runners often hit a plateau — mentally and physically — due to a concept called General Adaptation Syndrome (GAS). When your training becomes predictable, your body stops responding. Enter the SAID principle — Specific Adaptation to Imposed Demands — which explains why changing things up is key to unlocking progress. Karin shares how to keep your runs interesting without overtraining, burnouts, or breakdowns, using real-world tactics and military discipline. If you’ve been stuck in a rut, this episode is your blueprint for shaking things up and sparking new growth — without losing your back-of-the-pack spirit.