The process of excessive sweating basically takes place this way. Our body consists of sweat glands that control the intensity of sweat secretion in our body. These sweat glands produce perspiration due to both internal health factors and external factors like climate, outdoor activities, and so on.
However, for people who have hyperhidrosis or excessive sweating, the sweat glands are not able to control the perspiration. As a result, they seem to sweat even in normal situations, when there is no reason to sweat. It has been seen that people even sweat excessively in air conditioning or while swimming in a pool.