With every job, there's the big things and the little things. You get big, giant problems (a major client drops you) and little ones (your pen runs out of ink when you're trying to write something important). Similarly, you have big, enjoyable things as well (you make a great presentation and win an even bigger client).
I would offer that it's the enjoyment and appreciation of the small, little things that happen to you every day that leads to a happier life.
Sure, big things are big, but they're far more infrequent than the little things: you're early for a business meeting at a coffee shop and after making sure all is in order, you take a sip of your coffee... and notice that it's really, really good. You have a few minutes to relax and enjoy your surroundings and feel the steaming coffee vapor on your face as you hold the cup close. That's what I mean.
If you absolutely detest coffee shops but your job necessitates you spending a great deal of time in them, that's an awful lot of your day that isn't really enjoyable to you. If you're in the same situation but are indifferent to the coffee shop... it's neither positive or negative. But if you can learn to appreciate the little things about your job, you're miles ahead in being happy.
In my case, I spend a lot of time on stage. It's fun, it's great, but that's the big thing. One of the little things that I absolutely love is the drive home.
I don't mean "I really want to get home". Typically, by the time I get done playing, striking the stage, talking with folks who've come out to see the music, settling the tab and catching up with the bartender... it's late. Anywhere from midnight to 2am, usually. I load my gear out into my car and start home.
But the roads I'm driving on are designed for the traffic they handle at 8am and 5pm, not 2am. I have the luxury of having very few fellow travelers at that time. For all intents and purposes, I have 2-lane city streets and 4-lane highways all to myself.
In the summer, I put all the windows down, turn off the radio and listen to the wind and the sound of the road as it sails beneath me. (And yes, I drive the speed limit; when you've jumped out of airplanes dozens of times, any speed you can attain in a vehicle just seems passe.) I feel the car's weight shift as we enter a turn and feel the inertia wax and wane as we travel down and up hills. In the winter, the falling snow is beautiful in the headlights and the crunching of the snow under the tires is magical. In town, there's no one behind you to hurry you, so you can coast if the stoplight two blocks away is red (I love manual transmissions!). If you time it correctly, the light will have changed to green by the time you reach it. Eliminating the need for stopping and starting makes for a much smoother ride than is possible during the day.
In only a few hours, these same streets and interstates will fill with frustrated commuters moving at a crawl. But when I travel home from my job, it's a great reward at the end of what is usually a long, long day, and it's one of the little things that I look forward to most about this crazy life path that I'm on.
It's perhaps a natural consequence of the life and lifestyle that I've chosen (and that I live) that a great deal of my life is lived after many of those I know are in bed. We start playing music when many are in their pajamas and finish long after they've gone to bed for the evening. And yet, when we awaken (after far too few hours have passed) those same people disdain our disheveled looks because they've been up and active for hours. "But where were you last night at three?" I ask. "Long in bed. Why?" "That's when I got home from work."
The musician is much maligned because of the hours we keep. If I could play gigs starting at noon and ending at 5, and still be paid for them, I would. As it is, I can't draw a crowd at noon, and so that's why I'm in the bank line at 11:30am in my slippers and a baseball cap so that I can get quarters to do my laundry. Don't look down your nose at me, bub.