[sifar]

The point is worrying about results creates anxiety that takes away your focus from doing the job which results is lower performance -> subpar results - it is a recursive spiral. Also results are not "wholly" under our control. Hence avoid worrying about the results "while" doing it.

The final result of any action depends on a lot of external factors for e.g. one might develop a product, but whether it succeeds or not depends on other players, economy, luck and host of other factors that one does not control or know. This feeds into the first point about not worrying about the results.