It’s amazing how the human body can adapt. The last three weeks my long runs were 20,18 and 21 miles. This week my training schedule called for 13 but I didn’t really think anything of it. I went out like it was a “long run”. Surprisingly, I was done with the 13 before I knew it. It felt like I didn’t finish my run. I wanted to do more. About six weeks ago I sure would not have thought that would be the case. But, you body adjusts. Follow a well-thought out training plan that has gradual increases and a good amount a rest to avoid injury and before you know it, 13 miles is no problem.