I understand there comes a point where you can be so fatigued/stressed/distracted that continuing to work on a project will be less productive than if you were to step away to do something else.
Simply put, what is the best possible way to select a point to pause working to maintain optimal productivity?
In my personal experience I seem to have several "stages" of productivity loss. At first I notice my eyes strain, or a wave of fatigue coming on. If I continue to push through the issue may resolve itself. But, if the issues do not resolve I tend to have attention issues ("Maybe I should check my email?" or "I should call/check up on my family.."). In my third stage I notice an intense drop in productivity, often times working at half to one-quarter speed. If by some chance i'm still pushing through the final stage is me hitting the productivity wall - repeating the same actions over and over without noticing (essentially 0 productivity).
I'm worried if I stop working at the slightest notice of productivity loss that will instead lead to greater productivity loss.. how can I help find my "sweet spot" to pausing and refreshing myself?
Thanks in advance.