A method used during extreme conversion may be to exhaust the person, both physically and emotionally. During initial conversion this weakens their resolve and ability to make rational decisions. When they are converted, it keeps them pliant and removes opportunities to think about leaving.
When the body is physically tired beyond a certain point, the mind is weakened, laying a person open to suggestion and limiting their rational cognitive abilities.
A simple way of wearing a person out is to give them physical things to do. This may involve heavy lifting, but it is not necessary. Just being on your feet all day is enough to seriously tire most people.
In fact this low level of exercise can be sustained for longer but is ultimately more tiring. After a short burst of energy, our bodies make us rest. When you sit down after a long period of even gentle activity, it can be very difficult to get up again.
Long hours, working from dawn to dusk, both keeps people’s minds off other things and also serves to create a deep and very wearisome tiredness. If the person is active from dawn to dusk, they will sleep very soundly.
The level of exhaustion can be increased significantly by varying the hours of rest. When you are woken in the middle of the night, especially if you are in the middle of a period of deep sleep, then it can be as if you had no sleep at all.
Irregularity in work and sleep also adds to mental confusion as the mind seeks to create a circadian pattern and is unable to do so.
Shocks and stress
External shocks trigger the Fight-or-Flight reaction, with its attendant adrenaline arousal that builds us up, which is followed by the subsequent counter-reaction downwards.
The shocks may be created by unexpected events, from outbursts of a leader to sudden noises.
This constant up and down serves to accelerate physical exhaustion.
As well as physical exercise, mental exhaustion can be created by deliberate cognitive exercises. The brain uses a very large part of the oxygen in the blood stream, and additional thinking depletes this, leading to exhaustion as real as having done physical exercise.
When people are asked to learn new material or study great works, then the brain is engaged in understanding and committing to memory this new information. In particular if it is complex and uses new words and concepts, then further effort is required to integrate it into the existing models and modes of thought.
A variant on this is to be required to attend lectures during which an expert expounds on topics in which the person struggles to keep up. Like a straggler in a race, they force themselves onwards in the vain hope of keeping up with the athletes in front of them.
A further method is to engage the person in deep and meaningful discussions. Now they are being questioned and have to attend carefully, listening to what is said and responding to a degree that is to the satisfaction of the discussion leader.