What are the main approaches to motivate a workforce?

One of the main schools of thoughts to motivating a workforce is "scientific management" which believed employees only worked for money. Taylor believed in this and suggested to create the most efficient workforce, the tasks should be broken down into small, simple and repetitive tasks. They are then paid for each time they complete their task which should lead to increased efficiency. On the other hand, Mayo found that social workplace relationships motivated the workers more than pay. He also found that recognition from the bosses/supervisors also led to higher levels of motivation and, therefore, 30% higher efficiency. Maslow took this further and created a "hierarchy of needs" which showed the five sets of human needs, which a manager should meeting each level will lead to the most motivated workforce. Finally, Herzberg developed a two-factor theory which states to motivate a workforce (get them to want to do something) you have to address their hygiene factors, such as workplace and supervision, and their motivators, such as recognition and responsibilities, must be met.