Picture, if you will, a spinning top. When first released with a twist of the wrist, it whizzes around upright at high speed, describing tight circles, occasionally bouncing off nearby obstacles, but retaining most of its momentum.
As time goes on, however, the top slows, growing more and more wobbly until, tracing one last dramatic arc, it falls onto its side, spent.
The top is a metaphor. (To be clear: I’m the top.)