From The Evolving Self by psychologist Mihaly Csikszentmihaly:
"People who lead a satisfying life, who are in tune with their past and with their future—in short, people whom we would call “happy”—are generally individuals who have lived their lives according to rules they themselves created. They eat according to their own schedules, sleep when they are sleepy, work because they enjoy doing it, choose their friends and relationships for good reasons. They understand their motives and their limitations. They have carved out a small freedom of choice. Typically they are not people who want much for themselves. They may be ambitious dreamers, great builders and doers, but their goals are not selfish in any of the three senses of serving the goals of the genes, the culture, or the ego. They do what they do because they enjoy meeting the challenges of life, because they enjoy life itself."
My take: I often get sucked into the trap of doing what I think I "have" to do (what I SHOULD do) in order to live a good life.
But a really satisfying and meaningful life is one where "I should" is replaced with "I want to", where you pursue goals that you chose for the right reasons: for your own reasons.
"I should" is often a hint that I've adopted someone else's thinking.
This doesn't mean doing whatever you want: as Csikszentmihaly is careful to say, these enviable people still live according to certain rules. But they chose those rules themselves.
How to implement: Think about one area of your life where you wish you had just a little more freedom. Do you wish you could sleep in more? Wake up without an alarm? Work on more interesting projects? What's stopping you? Did you make the rules, or did someone else?
Further reading: I recommend checking out Csikszentmihaly’s books Creativity and Flow, which are contain many real life examples and studies + a plethora of actionable advice on creative living.