There is a widespread and I think it is wrong opinion that the reason for yawning is a lack of oxygen. In fact (and this has been proven in practice), the reason for yawning is relaxation after exertion. Yawning is a relaxation mechanism that the body uses to relax quickly. I personally had cases when in the classroom I yawned twenty times in a row and could not stop, physically feeling how the muscles of my shoulders and back were letting go. Often, yawning is associated with the desire to "stretch", this is the same element of this mechanism. If you learn not to overexert yourself (which I did), then you will stop yawning.
The reason for yawning, as far as I know, is the lack of oxygen in the vessels of the brain. Exercise requires more oxygen. After exercise, the amount of oxygen is less.
Before, there was an incentive to lose weight and exercise, how to return that willpower and endurance?