One of the hardest things for me about a PhD is the lack of concrete achievements. In work there were always things I had to get to someone by a deadline that were either good enough, or they were substandard and needed redone, but shortly after needing to be redone they had to be done. Done done. Similarly with previous studies there were essays and exams, there were things that were final, and there were grades that told me how I was doing. PhDs are different to that.