Great piece Adrian. I myself use a Momentum Conservation analogy. Momentum creates the ability to move. Going from rest to movement requires momentum. But once you are moving it's easier to stay that way. This ability to keep going without any effort is due to momentum conservation.
This helps me overcome my reliance on motivation. I use this mental model whenever I feel lazy to start important work. I don't wait for motivation because it is Momentum that creates motivation. Not the other way around.
Yes, the key is to propel yourself from rest to a flow state (i.e. perpetual movement). Once you're in movement, it's hard to stop (i.e. you need a reverse momentum or an external force).