Anybody care to explain?

I'm guessing the longevity was actually a divine gift wholly independent of Phynaster, but he figured it out first and capitalized on the realization. Learn to walk like Phynaster and you too could live an extra hundred years! Also available from Phynaster, snake oil - it has a 101 uses!

Awesome username and avatar by the way.

There isn't much on it. There are the six walking ways in the Sermons which are paths to apotheosis. A more efficient way of walking could be a similar metaphor.

Or you know, do https://www.youtube.com/watch?v=jqOSR7KX_ik, but more efficiently.

The altmer will make anyone a culture god if that person shows or discovers a way to lengthen an altmer's lifespan, even by 1 second.

Imagine how much money someone could make selling the altmer knowledge on healthy eating and exercise programs.

Such Imperial thinking. The idea that the Altmer has the desire to gorge his food and is willing to forgo the proscribed movement routines. There is no such individualism amongst the Altmer. Such variation is the mark of Sithis.