We are two neuroscientistswho study how the brain and body respond to stress and how those reactions shape perception. We hypothesized this physical stress would trigger a slight change in how their brains would interpret physical sensations and change their ability to tolerate physical discomfort; this was the recalibration step. What we foundWhen we first saw the results, we were amazed by how much a short stress induction could affect people’s perceptual responses during exercise. The second effect is a short stress surge. The key is to keep the challenge short, safe and within your limits, especially on days when life is already stressful.