Being tortured to death would be pretty hard, as seen in those movies... where that guy traps people and makes them do crazy shit (ie. rip open ribs to get rid of bomb or something). Forget the movie.
I can handle drowning. I constantly have these dreams, where, i put my head in the pillow or something so I can't breath. My mind wakes up and I consciously try and make my body wake up, as like I said I can't breathe and I think I'm going to do
I get to the point where your body physically forces you to take a breath, and if it can't do so you either fall unconcious or die
I can handle diseases. I think it would be a rather peaceful way to do. You know a timeframe, you can do the things you want to do and pay your respects before going. Shot, stabbed whatever I could do. The pain is only temporary, all pain passes.