Samuel Beckett’s Not I
Samuel Beckett has written some great plays. In Not I he wrote a play where only the mouth is shown. The great actor Billie Whitelaw did it in 1973 and you can see the remarkable result by clicking on the image of Billie Whitelaw.

When Lisa Dwan performed it in 2006 she met Billie Whitelaw shortly afterwards and they compared notes.
“We immediately swapped our trench stories. I told her how I strap my head into the banisters at home and babble away for hours training my mouth and diaphragm to speak at the speed of thought without moving a millimetre.
Billie’s head by contrast had been strapped to a dentist’s chair, where once during rehearsals she collapsed and Sam (Beckett) rushed over to her saying ‘Billie, Billie! What have I done to you? What have I done?…. and coming to she replied, ‘I really don’t know how to answer that Sam.’
We agreed that the hardest element of all – aside of course from the neck strain, the hernias, the stroke inducing stress of it and the development of pelican like jowls for spit collection as there is no time to swallow – is attempting to control and suppress one’s own internal Not I. In the nightly terror that the piece always produces – the thoughts like vultures hover above the lean lines.”
There are solutions out there that can help actors rest/recover from giving such strenuous performances nightly.  Something other than work outs, massage and acupuncture, vodka and the rest.  Some paint or draw , others meditate.  The relentless run of a play can drain the strongest.