Hard work is deliberate practice. It’s not fun while you’re doing it, but you don’t have to do too much of it in any one day (the elite players spent, on average, 3.5 hours per day engaged in deliberate practice, broken into two sessions). It also provides you measurable progress in a skill, which generates a strong sense of contentment and motivation. Therefore, although hard work is hard, it’s not draining and it can fit nicely into a relaxed and enjoyable day.

Hard to do work, by contrast, is draining. It has you running around all day in a state of false busyness that leaves you, like the average players from the Berlin study, feeling tired and stressed. It also, as we just learned, has very little to do with real accomplishment.