I like the mana and hit points concept.
Being from Alaska, I was aware of seasonal depressive disorder long before I realized how much it was effecting me. I never noticed myself getting down, what I noticed was the big, dumb grin on my face around March. Recently I realized that even though I am now in southern indiana, it still effects me.
Since I want to stay around family, it is unlikely that I will ever move close enough to the tropics to remove this challenge. I need to find solutions. My current big discovery was walking a couple of miles in the middle of the day when weather allows (lunch, breaks at work). It didn't help overnight, but after a week or two I again feel like God's his heaven, the lark's on the wing, and my enthusiasm for life is coming back strong.
My wife has some pretty bad energy and muscle cramp and pain issues. Because if that she has resisted walking or spending much time outside (in fairness, summers here are way to hot and humid for comfort, winters are cold and when it's warm enough, rainy. Now, though we are in spring. We're trying to get a house ready to
sell, so she dragged her butt outside and started working in the
yard. After a couple of weeks, her aches and pains are dramatically reduced and her energy is probably increased 5 fold.
When we feel bad we want to lay around and watch the idiot box (tv) or get on the other idiot box (the internet or
games) when sometimes what we need to do is something shaved monkeys are designed for, get out in the bright sunshine, some nature, and move! It is a pretty good spoon producer, although not always showing immediate results.