Worse Than Death

Torture (emotional and physical) mainly. By emotional I mean for example having to watch every single person you love be killed or something of the sort)

Depression. Having been there, there's a reason suicide comes with it so readily. God, I just wanted to stop hurting so many days. Anything to not have to feel reality anymore.
Other than that, complete isolation or slow torture meant to keep you alive but in agony. Sometimes death would just sound lovely. (I just realized that both of those are descriptions/parts of depression. Whoops.)

Eternal life

Ruin them completely both physically and mentally. Make pain constant. Make sure they don't know what's real and what isn't anymore. Make them feel what their victims went through, but worse and/or repeatedly.

Studying for the test and still failing.

Ooh! I know this one.
Give them food, not alot, but enough to feed them, and then no water.
They have to get their water from their food, but you'd give them a lot of salty food.
See how long they last.