Re: Einstein, Picasso & Life-energy.
Excellent questions these are!
The physical lifeforce is indeed limited and can be overspent, or spent within a relatively short period of time. Most people in the fast modern world racing against time to make it use up this resource too quickly and end up too weak or sick to even enjoy the later years of their life.
But then there is the energy that you have mentioned. It is the spiritual energy. You tab into it and increase it when you are truly creative and enjoy be pleasure of creating, versus just trying to achieve a set goal. Creative artists are in the flow of this inexhaustible energy, the energy that sustains spirit itself. It it always there, and doesn't diminish when the body dies. It is the purpose of our earthly existence to become fully infused with that spirit energy and make use of it like we use electricity to run this computer.
Routine work, as experienced by millions of workers, stifles creativity and ages the body. Using the mind in numerous different creative ways brings spirit's energy into the cells of the body and rejuvenates them. One day not too far from now, we will create devices that existed hundreds of thousands of years ago to fully rejuvenate the body and keep it that way for as long as it is desirable and in accordance with divine purpose and need.