Endurance is one the four qualities to be trained. Imagine getting a bunch of groceries delivered to your house in a steady stream for an hour. You will bring the groceries in and put them away to give room for more groceries. During something like distance running your cells have to process the food as you go otherwise the debris would build up and you would have to stop and recover.
If we stay with this analogy and compare it to the other trainable intensities, we could say that posture is you closing your doors not to take any deliveries so you can finally catch up and organize all the stuff already in your kitchen. Actually, the doors are not completely closed during posture because if you have to be awake enough to hear a siren just in case of an emergency. It is during sleep that the doors are more completely closed. Excitability is when the doors are maximally opened and you can take a whole truckload of groceries into your house. Of course you will not be able to put them away right then because you will not be able to keep up with the influx of groceries.
Pure endurance training is repetitive and because of that you mostly tune out the outside world at the same time you are very awake. Your brain then starts to process all the information stored in your memories at the same time the ignoring hormones like serotonin block fear and pain, meaning it is a unique type of processing in which you can put a lot of links together at the same time you are idealistic in your thinking.
