For all the references given on those resistant to change, it would seem that this would be an easy muse.
In ancient times, and so perhaps we are still in ancient times if we're musing on this question, but the theory to life (for lack of a better phrase), was that people had to find ways to survive. Yes, I'm talking about the hunting and gathering times, just before people began organizing societies that would bring us up to current times, when work (as I heard phrased) "wasn't supposed to be fun…that's why it was called work!"
Needless to point out… we're 'modernized' now, where things get a little technical, or perhaps I should point out, where I contrast yesterday against today, believing modern societies afford us the opportunity to select how we choose to make a living. In truth, all 'work' is work, with the up and down nuances. This still shouldn't preclude us, particularly today, from selecting a 'career' that gives us the most satisfaction, so that those who we serve benefit as well.
What did Dr. King say, "If a man is called to be a street sweeper, he should sweep streets even as a Michaelangelo painted, or Beethoven composed music or Shakespeare wrote poetry. He should sweep streets so well that all the hosts of heaven and earth will pause to say, 'Here lived a great street sweeper who did his job well."
I think I could spend a night and the rest of my days listing the benefits of being able to leave work at work, getting in a good night's sleep, not only earning an earning, but knowing others are benefiting from the fruits of our labor. But for sake of avoiding being too repetitive, yet to be clear, it's necessary to include here how I always wanted a writing career. However, to get to my first career choice, it took quite a few derailments (experiences my father told me I'd need), plus the advice of a counselor who advised me to pursue a business degree because… "a business degree can be applied to any career field," she said―the best career advice I ever received, even if I sulked after hearing it. And by the way, I'm thankful to have always been afforded this opportunity to be picky about where I worked. I like the idea of loving 'my job,' and love even more, patronizing businesses where employees love their jobs.
All to say, just because you love your job, doesn't make it any less work. And without a doubt, if what you love doing is to benefit others, it will benefit others and reward you right back. The fact that most of us, if I should dare include, struggle… whether doing what we like or don't like so much, doesn't make our jobs any less of a career.
Hobbies, by all means, are the things we do to solely pass, or pacify time. One of my favorite hobbies is playing Freecell, or Solitaire, or Scrabble maybe...