7 mile hard long run

I took yesterday off. My body needed it. Today i went for my 6.9 mile loop through dumbo and fort greene. I did it in 44:40 for a pace of 6:28/mile. Up until about mile 5 I was feeling pretty exhausted, but I also didn't realize I was running that fast, so it makes sense I was so tired. After that I did about a mile real slow for a cooldown to get in 8 miles total for the day