In physics, power is the rate of doing work per unit of time. With work being a force applied over a distance.
As a consequence, power is the ability to use strength. For example, when doing your workout, strength will be the amount of weight a contracted muscle can support.
When a muscle is strained or stressed, there is less it can support. Its ability to generate power is reduced.
The same is valid for the brain.
This is most visible when playing golf. Any distraction shows. Executing a swing works best when following this principle: “the best conscious effort we can make is to be clear with our goal and to keep from interfering with its execution” (Tim Gallwey, The Inner Game of Golf)
The effort to control and correct execution stresses the brain, reducing its strengths and the power it can develop.
Why do we stick to ruminating then?