Obviously crucial stuff, since you have a physical body that is going to be doing an endurance thing. So yeah, your body needs to be ready.
But I'm noticing something about the people who are doing the really crazy and amazing stuff. They still talk about the physical and they talk about the training.
Then their voices get kinda low, thoughtful and quiet. And they start talking about the fact that it's the mental stuff that really makes or breaks you.
It's true, of course. Once your body is prepared, and you can't skip that, it's revolves around what's going on with your mind.
This is especially tough for swimmers. We spend enormous amounts of time in our own heads. Our minds run all over the place. If you have a good imagination, it can also be very freaky.
I have a good imagination. The movie Jaws came out when I was a child. I'll never see it. Am I scared of sharks? Yes, I am. Seaweed brushing against me when I am body surfing makes me shudder. The intellectual knowledge that I am never more than about 25 yards from a shark when I am playing at the beach is something I have to beat down hard, but I do because I want to enjoy being in the water. I can tell myself that few are human aggressive, that I don't do many swims at twilight, that there are almost no shark attacks anywhere I am likely to swim on regular basis and the thoughts still come back. Shoot, I have found myself imagining all sorts of scary denizens of the deep when I am in the confounded pool. This is not where your mind needs to be when you are swimming out in the open water. So, I have to guard my mind and imagination carefully.
This has me mentally griping right now. One of my favorite authors has just come out with a new book, and I can't read it. Not if I want to do open water swims and not psyche myself out. This is worse than being on a diet while training, I tell you!