For each one, the mental preparation is different, so this is my personal impression after many Caminos.
For me there are several "mental stages" along the Camino, which more or less coincide with the different weeks of the journey. Obviously if the Camino that you do is short, these “mental stages” are concentrated and can last days instead of weeks.
The first week is the “physical week”. Your body must acclimatize to walking 20 or 30 kilometers a day every other day. It’s the week of the first blisters, the leg pain after finishing the day and the week in which you discover that you have muscles that you didn’t know existed. Almost your whole mind is focused on your body and its state. But it’s also the week in which you discover that there are some "Elves of the Camino" that every night, while you’re sleeping, work silently in your body to restore the deteriorated muscles and leave you ready to walk the next day. It’s really magic¡¡¡.
The second week is the “Mental Doubt week”. It is the week of uncertainties, of "What the hell am I doing here?" and the "I'm not going to get it." It is the week to look at train and bus timetables and to think about taking taxis. The worst are the afternoons, after finishing the stage and resting; when you realize that tomorrow you have more of the same and your whole body and mind asks for rest. But your body is actually becoming more and more physically adapted to the walk and after a night of rest and the action of the "Elves of the Camino", starting in the morning is becoming easier and easier.
The third week is the “Spiritual Week”. Once doubts have been overcome and physical problems moderated, your body and mind are used to the daily routine. It is the moment when you can let your mind float without worrying at every step about that pain you have or that mountain that comes next. In a complete
Camino Frances from SJPP, it coincides with La Meseta, which is the ideal place to let your imagination run wild and focus on the problems you came to solve or meditate on the Camino. This week the Camino can be enjoyed in all its fullness, even when you have to continue taking care of your body like the first day.
From the fourth week onwards is the time when you enjoy the Camino the most, your physical and mental problems are resolved or controlled, and you are already focused on the goal; that you know is close but you hope that it will never arrive. You enjoy the walk, you enjoy the afternoons of rest and your companions, you enjoy the towns you pass and the ones you arrive at; you even get to enjoy the ups and downs. It is the moment when you begin to wish that this would never end and that you begin to think with regret about returning to the daily routine.
Personally, what I find most difficult to get rid of throughout the Camino is what I call "Negative Anticipation", which is very normal during the first few days. "Negative Anticipation" are those recurring and magnified thoughts about how hard tomorrow's stage is going to be, how difficult that mountain I haven't reached yet is going to be, how much that foot that gives me problems is going to hurt... It is really a "killer" of morale on the Camino, especially in the first days/weeks. You anticipate all the bad things that can happen and you magnify them. And then, when tomorrow's stage finally arrives it’s not as bad, the mountain to climb is not that difficult and the sore feet are usually not as bad as you thought; and if they are, you handle it. Knowing that these thoughts are "Negative Anticipation" and that they are normal, helps a lot to combat them. Personally, as soon as I feel that I am having a "Negative Anticipation" I try to turn it into a positive one thinking, for example, about the magnificent place that I will visit and where I will sleep after the stage, in the stops to have a drink that I will make, in how beautiful will be the views after climbing the mountain or that the foot pain is actually bearable and will pass in a few kilometers...