Ever notice how those crazy people who workout all the time say they “feel great” afterwards, even though whenever you go to the gym for your once-yearly, new-year-new-me regimen you just feel like crap? Well turns out there just might be a genetic reason for that. Dutch researchers have identified a possible genetic inheritability aspect to whether you receive that endorphin rush after working out. We’re being a bit cagier than normal when describing the results of this study since the causal relationship hasn’t been verified yet–so maybe working out often changes how the body responds to that exercise. No results yet on how the hell those people were able to begin exercising regularly in the first place.