Advice toward easier and profitable fasting
Your body does not start to clean itself when the fast begins but works on the task constantly. If you eat lightly (more vegetables and less processed food with preserving substances) and drink more water and less alcohol before the fast your body will have less to clean on the starting line and you will reach further and experience less of a delta in the process. The result will be a healthier more vibrant feeling and a greater affect over time on you aging and inner workings
Trying to do meditation or work on a difficult subject once in a month is akin to being faithful to your wife one hour a day. Neither are going to end up well. If you plan to meditate or perform exercises over the fast start practicing daily or whenever you can. You will get a lot more out of the work you are doing and experience less pain.
If you are planning to avoid water as well as food start drinking a bit every hour a day before the fast to allow the body to adjust and gently take in more water without any harmful affect and with a greater release of toxins from the body all throughout the fast.
Since our movements and actions continue to affect the body and mind after the physical work is over it is best to do the strenuous work in the beginning of the fast unless you are purposefully testing yourself. An example would be to do your pushups and squats in the first hours of the fast and coordination work toward the end depending on your current focus.
Preparing the body toward handling stabs with the repetition of scratching is logically unsound. Don’t expect short breaks from eating to be exactly as a full one to three day water and food fast or a full week food fast. Be humble and know from there when to push and when to give way. Remember the road is important but it is not the goal.