Top 16 Mistakes to avoid when your running is getting harder. You’re not maintaining your Gut Health. Your shoe doesn’t fit. You Don’t Have a Proper Training Plan. You are not listening to your body. You are calorie-starving yourself. You are not running enough. You don’t have any variation. Running is not your priority. Running is not your priority. You are over-training. You are dehydrated. You drink too much water. Not Warming Up Or Cooling Down. You are under-fueled. Not re-fueling after running. You are low on motivation.