One has to complete this task in the 4th year of the PhD. It's part of our required curriculum. It typically takes a while to find a topic to propose because thinking of a novel idea is HARD. Then, investigating and digging into the topic to propose it is also hard. It's a great critical thinking exercise; however, most students find it to be an annoying interruption of their research, and time consuming to do, which it is. Even so, I'm excited. It's actually kind of fun - ONCE you have a topic - that is. Trying to think out what to do - it's like a great big brain puzzle.
I picked HIV drug therapy and thought of a unique drug concept to treat HIV. Now I just have to figure out how to make it actually WORK. (...) Ha ha! Wish me luck. I'm a glutton for punishment.