I'm bunching these all under one document, since they're all loosely related.
Renegeration
We should have a Terraria-style regeneration system. That is, health naturally regenerates over time, and there can be items that either give a burst of health, or increase regen for a period of time. Maybe we could have blocks like the Terraria campfire, that give a passive regen effect.
Stanima
Stanima would be used for non-trivial movement, that is, anything that's not walking, crouching, crawling, or sprinting. Performang an action would take a certain amount of stanima over a period of time, and you won't be able to do actions once the stanima runs out.
Stanima would regenerate over time, so between actions you need to take a break.