Basically i'm suggesting the way the health works in Metal gear solid.
specifically GOTP
Anyways,
You have psyche, (stamina in the third i thought) which lowers as you're attacked and in battle.
If you are OUT of battle, your psyche regenerates. Low psyche leads to low health regeneration, which leads to (you're dead.)
I'd like a health bar to go with it too, if that'd be possible.