Interesting, thanks. Still, it takes at least a bit of initial grit to do that one pushup - especially every day.

You need to get the ball moving with following your own instructions. The first tasks don't have to be useful or related, just doable. Eg force yourself to blink. Then raise one arm. Then stand up. Now you are half way to doing the pushup. Ignore the silliness of it all, and keep going. With each progressively harder step, you gain more momentum and more energy to take bigger steps.