I am tired because I may have worked too hard. At least, this is likely to be my excuse. The reality could be that I have worked too long. There is a subtle but profound difference between working hard and working long.
Working hard is not a factor of time. Instead, it is a factor of intense input. However, working long is merely a factor of working long hours, irrespective of our input.
It is often good to unpack if we are working hard or long.
