Slowing up or decelerating is a natural process that occurs in various phases of life. This process can be described using synonyms such as lagging, retarding, stalling, reducing speed, or delaying. Occasionally, one may use expressions like losing steam or momentum or tapering off to indicate a decrease in activity levels. In contrast, augmenting or speeding up may be used to connote a surge in activity levels. The word 'brake' could also connote a reduction in activity or delay. However, it's essential to note that reducing speed or slowing up shouldn't be confused with cessation since they connote a decrease in pace and not a complete stop.