Could it simply be because of exercising providing much needed break from focusing on worries in one's life? If so, any activity that one can enter into a state of flow can be beneficial.
No, the article's whole assertion is why exercise specifically causes these benefits. I don't know how "oh, maybe I just need to stop worrying about things to reap these same benefits and activate these same pathways" is a possible take-away from the article.
Though it's tempting wishful thinking because it saves us from leaving our computer chair. "Maybe I can just enter a flow mode learning Elm/Rust instead of exercising!"
It's easy to say, but if you are focusing on what worries you, without doing anything to work toward or resolve what is worrying you, it's really just wasted mental energy. Once you can be honest with yourself about having done everything you possibly/reasonably can to mitigate whatever you are worrying about, then you can let it go.
There is even a tendency to fool ourselves into thinking that we have broken free of it, whilst still having that feeling of worry simmering in the background.
