The hardest stage of the PhD

I recently ran a poll on Twitter, asking people for their experience on what they considered the hardest stage of the PhD. The results, and personal stories, are quite interesting. For 45%, the end of the PhD and the writing stage are the most difficult phase - I had expected this percentage to be higher (say 67%), based on my perception.

For myself, the hardest stage was at the end - not the actual writing, but the patience I needed until my promotor had time to read my draft. Patience is a virtue, but unfortunately not one that I possess...