Where kinda mindset do you need to have to run a marathon, and finish in the top 10 or come in first?

I’m thinking you have to be in great shape and conditioning but it has to be mental if we assume most of the runners are great runners and have plenty of stamina, endurance. Then it must become a mental thing. I wonder where your mind is mentally before you start the marathon and after completing it knowing you won or came in a high place.