For instance, one only needs to know that:
The gem cannot be polished without friction
Or that:
Under pressure, everything becomes fluid
Well I suppose this last one isn’t quite true - nevertheless I hope you get the point.
Any knows of more physics analogies that can be applied to the mental?
Always a little bit of liquid remains in the bottom of a glass, no matter how many times you try to empty it.
I have to FORCE myself to do everything. Lol. 
To borrow from bruce lee…
“Water can flow… Or it can crash… Be formless, shapeless, like water… Be water my friends”
Not really a physics analogy.
I personally like to think that as I focus on standing in the current… I choose what parts of me are eroding away. It is a choice. Let the evils of this illness beat and corrupt you, or face your fears and let it refine you.
One way or the other… I think everyone ends up opting for the latter. That is… So long as they don’t get lost along the way.
Ah but to add one thing… Neuroplasticity… You can program your brain. Choose what you want to keep, let the other things fade away.
Thought of another one, the law of conservation of momentum:
In a closed system (one that does not exchange any matter with its surroundings and is not acted on by external forces) the total momentum is constant.
ah good one… seoarate the mind from environmental influences… especially in social environments