OK, so when I said that lithium is trying to kill me, I was exaggerating just a tiny bit. See, lithium and I are in committed, love-hate relationship. She gives me a gives me a semblance of sanity, and in return I continue taking dangerously high doses of her every day. We've been together for almost five years. I frequently dream of breaking up with her, but we both know it's never going to happen.
FYI, if you're in the business of taking medical advice from flippant blog titles, then let me very clear: lithium makes my life hell, but my life on lithium is nowhere near as hellish as it would be off it--as it was before I started taking it. Basically any hardcore mood-stabilizer or anti-psychotic is not going to be pleasant; only you can decide if it's worth it.
That said, there are some circumstances under which lithium will try to kill you. If you become too dehydrated while taking lithium, it could do serious damage to your liver and kidneys. Don't do go without water for any lengthy period of time. Not even if it's Yom Kippur. Ask your rabbi. They'll understand. (You don't have to tell them you're taking specifically lithium.) They may even tell you it would be a Desecration of God's Name to endanger your heath in such a way.
And, of course, if you swallow two months worth of lithium in one go, it'll do its best to kill you, but, trust me on this, that's not a very good idea.