In order to become a professional in a given field, you need to start off by working very hard. The reason is that there’s a lot to learn and you’re competing with other people who are further along the learning curve than you are.
However, the more you learn in a field, the less there is left to learn in that specific field. Although learning never ends even in a specific field, the pace of learning declines.
In addition, many people who were further along the learning curve when you started off in the field drop out, and you surpass many others as a result of your hard work.
When this happens, somewhat paradoxically, you work less hard as you gain more experience.
However, this doesn’t mean that your output declines. To the contrary, since you’ve learned which activities contribute to what you’re doing and which don’t, you don’t chase after everything as you used to when you first started off.
So you get to work less hard, but more smartly, while continuing to see increases in your output.
This continues to be the case unless you decide to enter a new field. If you do so, you get to experience the challenge but also the joy of once again learning something new.