If you're a marathoner (or a marathoner in training), you know a unique form of determination. Setting out to accomplish something that only 0.01% of the global population has done — running 26.2 miles, the equivalent of 105-plus laps on the inner lane of a standard running track — entails a level of persistence that may warrant at least one person in your life calling you crazy. But is there a difference in the persistence of a first-time marathoner, aiming simply to finish, and a two-time Olympic marathon runner like Liz Yelling, looking to set a new personal best? We want to understand the science behind your grit and tenacity. What's happening in the brain when we commit to completing an endurance race like a marathon? We asked Dr. Beth McQuiston, a neurologist and medical director at Abbott, and she began by pointing out that every person’s brain is different. For some, their prefrontal cortex, which connects with other regions of our brains to regulate emotions, is more prominent, influencing dopamine (a chemical released in the brain that makes you feel good) when training. For others, certain areas of their cingulate gyrus, a part of the brain that impacts emotion processing, may be more active, enhancing focus, spurring tenacity and yielding positive feelings. For others, their amygdala, a roughly almond-shaped mass that impacts the experiencing of emotions, may be sparking anxiousness or nervousness to drive them. But truly, whether you're a world-class prefrontal cortex-dominant runner or a beginner prefrontal cortex-dominant runner, you're likely experiencing the same drive. Sure — having marathon experience may seem like it makes your upcoming race feel less daunting. But we all can relate on how it feels to set and achieve a goal, regardless of experience.