The most successful and happy people in the world avoid multitasking like the plague

"Task residue" is the leftover cognitive load that occurs when someone switches between tasks. Multitasking has a massive amount of task residue, where the time and energy spent on one task affects and lowers the performance of another. Task residue will cause a decrease in productivity, as well as an increase in anxiety and stress.  When a person multitasks, their brain is constantly switching back and forth between tasks. This switching requires energy, which can quickly drain a person’s mental resources. As a result, the tasks being performed are not done at full capacity, leading to a decrease in productivity. 

Multitasking can also be called "Dopamine Switching", because as the activity switches, so does the source of dopamine. Dopamine is what makes the mind stay alert and focused on something, which can be detrimental when there is a frequent...