3 weeks today I will on the start line of my first marathon. I am running to finish which I estimate will take me 5hrs 15/20. Training hasn't been perfect but I got the miles in, the past month I have been focusing on my fueling which is going well also. My problem is my head! When I run I overthink after 10k, I start to panic and feel like I'm going I can't go on. It's very annoying and has happened my past 3 long runs. Has anyone any tips on how to over home this? I want to really enjoy my first marathon and take in the atmosphere and finish feeling proud of my achievement. Thanks