I'm looking over the OLD corebook and I can't for the life of me find any rules about health advancement. I found the part about starting health being a roll of endurance, willpower, and the hardy skill, but there's no indication that characters ever get more. Is health fixed at chargen? Can characters only increase their health in play by taking one of those stats or that skill? Do they just roll another d6 and add it every time they do (I'd assume you wouldn't reroll the whole pool, amusing as that would be)?