People who don't pay attention to their own inner state are rarely happy. Those who don't use reason to guide their thoughts and feelings will always be miserable.
Always keep these things in mind: What is the nature of the whole universe? What is my own nature? How do I fit into the bigger picture? What kind of part am I in what kind of whole? Remember that no one can stop you from acting and speaking in ways that match your true nature as part of this universe.
For not observing the state of another man's soul, scarce was ever any man known to be unhappy. Tell whosoever they be that intend not, and guide not by reason and discretion the motions of their own souls, they must of necessity be unhappy.
These things thou must always have in mind: What is the nature of the universe, and what is mine--in particular: This unto that what relation it hath: what kind of part, of what kind of universe it is: And that there is nobody that can hinder thee, but that thou mayest always both do and speak those things which are agreeable to that nature, whereof thou art a part.