By example. Seriously.

I've been plenty of places where the edicts are passed down to the... "little people". They/we can end up jumping exhaustedly through endless rounds of process.

Then, the shit hits the fan, or a senior manager simply can't be bothered, and process is suddenly out the window.

Imagine the impression that leaves on everyone who's been running the process maze.

Demonstrate that it matters and serves a purpose. And keep it sane.

All the rest is just talk.