When I'm programming, a lot of the time it's in order to make easier something that's definitely more boring than programming.
Most programming might not directly give joy to people, but most people who work in accounting are probably happy they can use spreadsheet software instead of spending hours per day doing their own arithmetic.
Musicians might be enviable—well, at least those that are sufficiently successful to work on their own terms and have a good income, which isn't easy to attain. Touring probably isn't for everyone. And fiction writers... I'm not sure they're so cheery and satisfied in general.
Here's David Foster Wallace about writing Infinite Jest:
The best metaphor I know of for being a fiction-writer in the middle of writing a long book is Don DeLillo's "Mao II," where he describes the book-in-progress as a kind of hideously damaged infant that follows the writer around, forever crawling after the writer (i.e. dragging itself across the floor of restaurants where the writer's trying to eat, appearing at the foot of the bed first thing in the morning, etc.), hideously defective, hydrocephalic and noseless and flipper-armed and incontinent and retarded and dribbling cerebro-spinal fluid out of its mouth as it mewls and blurbles and cries out to the writer, wanting love, wanting the very thing its hideousness guarantees it'll get: the writer's complete attention.
The damaged-infant trope is perfect because it captures the mix of repulsion and love the fiction-writer feels for something he's working on. The fiction always comes out so horrifically defective, so hideous a betrayal of all your hopes for it—a cruel and repellent caricature of the perfection of its conception—yes, understand: grotesque because imperfect. And yet it's yours, the infant is, it's you, and you love it and dandle it and wipe the cerebro-spinal fluid off its slack chin with the cuff of the only clean shirt you have left (you have only one clean shirt left because you haven't done laundry in like three weeks because finally this one chapter or character seems like it's finally trembling on the edge of coming together and working and you're terrified to spend any time on anything other than working on it because if you look away for a second you'll lose it, dooming the whole infant to continued hideousness). And but so you love the damaged infant and pity it and care for it; but also you hate it—hate it—because it's deformed, repellent, because something grotesque has happened to it in the parturition from head to page; hate it because its deformity is your deformity (since if you were a better fiction-writer your infant would of course look like one of those babies in catalogue-ads for infantwear, perfect and pink and cerebro-spinally continent) and its every hideous incontinent breath is a devastating indictment of you,on all levels . . . and so you want it dead, even as you dote and wipe it and dandle it and sometimes even apply CPR when it seems like its own grotesqueness has blocked its breath and it might die altogether.
The whole thing's all very messed up and sad, but simultaneously it's also tender and moving and noble and cool—it's a genuine relationship, of a sort—and even at the height of its hideousness the damaged infant somehow touches and awakens what you suspect are some of the very best parts of you: maternal parts, dark ones. You love your infant very much. And you want others to love it, too, when the time finally comes for the damaged infant to go out and face the world.
But wanting other people to love it, now, means hoping that others somehow won't see the hideous infant as you see it—as a grotesque, malformed betrayal of the very possibilities that spawned it. You hope very much they'll look at it and pick it up and dandle and coo and fall in love with something they see as pink and whole, as the sort of transcendent miracle that only whole babies and unwritten books are.
So you're in a bit of a dicey position: you love the infant and you want others to love it, but that means that you hope others don't see it correctly. You want to sort of fool people: you want them to see as perfect what you in your heart know is a betrayal of all perfection.