Let me explain the title:
What kind of goals you have had or currently are working on that have been the hardest to reach? It can be anything - raid boss kills, certain items, achievements, titles, completing a JP, completing a personal challenge of yours etc.
Keep in mind I want to hear about things that personally mean something to YOU, not just a "legendaries are too hard to get" or "raids are inaccessible". I want to hear about things you have worked on/are currently working on/are going to work on!
For me, the Fractal God title seems like a big, and a long term goal.