Interests and aptitudes. Possibly I mean Aptitudes and interests. Know what you like, know what you’re good at, and know the difference. It can be a chasm*.
Plus, in my experience**, being in the right place at the right time, and being able to recognise them as such, is a big part of being successful/happy (the same thing in this context: nobody ever says “I want to be a failure”. Not out loud, anyway). Positive thinking, making your own luck… for all that they sound patronising, they seem to work.
* two paragraphs of me me me that you don’t need
** and three more