• I think emotional stability is essential for long-term trading success.
• Mental stability is less essential in my opinion.
I'm thinking of several "evil geniuses" (not personal acquaintances), who are brilliant in their careers, while being certifiably mentally ill.
On a humorous note, in the modern BBC tv adaptation of the Sherlock Holmes saga, Holmes (played by Benedict Cumberbatch) tells Watson, "I'm not a psychopath. I'm a high-functioning sociopath." I think there are high-functioning traders, with serious mental problems. Maybe even a couple here on this forum.
• And I think that physical vitality is least important.
I personally know traders who suffer from serious physical disabilities, but are able to bring mental focus and emotional stability to their trading, and as a result they are able to trade successfully.
In the world of theoretical physics, Stephen Hawking comes to mind. Despite severe physical disability, he has distinguished himself as one of the great physicists of our time.