And the experience I was mentioning is well summed up by "develops its own inertia". You become fine tuned at adjusting activity to keep inertia in some range,

And the experience I was mentioning is well summed up by "develops its own inertia". You become fine tuned at adjusting activity to keep inertia in some range, avoid the zero which would cost you long time to recover that inertia, but don't over work yourself. Cause a life of overworking is dreadful, the key is finding the sweet spot. I even think we're build for that, the right kind and amount of stimulation keeps life interesting.