.What if one of the most powerful indicators of your health isn’t how fast your heart beats but the space between each beat?

In this episode of Becoming Limitless, Dr. Elie sits down with Salim Najjar, widely known as “that HRV guy” and creator of The Art of the Heart, to explore how heart rate variability (HRV) offers a deeper window into the nervous system, stress, and overall human performance.

The conversation begins with Salim’s personal journey, from high-performing engineer and biohacker to someone forced to slow down after his body broke down under chronic stress. Despite optimizing every metric: sleep, fitness, productivity, he discovered that true health wasn’t about doing more, but about understanding how the body responds to stress.

At the core of the discussion is a powerful idea: HRV is not just a number, but a ref ...