So, I was aiming to run a sub 18 in this 5k I ran recently and ended up just 19 minutes, I've noticed over the years some days are just worst than others, that day was one of them obviously, so why are some days like this? I'm going to make up for it this fall. Here's a few contributing factors, I think, i added an extra workout per week, rather than my regular one, I also was getting terrible sleep, and running more milage than i normally would do, also was not swimming as much and have not been doing core exercises. Could this have lead to my very bad race day?