Deceleration is the opposite of acceleration. It is the rate at which an object slows down and it can occur suddenly (crash) or over a long period of time (controlled descent).
People may choose to slow down or they may be forced to do so. For instance, a business may need to decrease it's rate of production due to lack of demand or an organization might need to close because they are bankrupt.
Moving objects have momentum—as do people when they are focused on achieving some objective.
Slowing down after reaching a goal, to rest or regroup, is a natural part of modern life. It can be difficult for people and organizations to reduce speed, especially when they are used to being constant motion. The energy that has been driving someone for so long needs to go somewhere. Maybe it goes into another project, business, or hobby. It has to shift.
The shift is like a pressure release.