One of the understated joys of parenthood is when your children lovingly mock you in the form of a Pokémon card.
I've been an off-and-on piper for almost fifteen years and consider myself solidly mediocre (as the picture here evidences, I'm just good enough to play a tune in church on St. Andrew's Sunday--but only if the church is big with lot of echoes and the congregation is especially charitable). The bagpipes are actually the fourth instrument I've picked up since childhood. My mom very much encouraged my learning classical music when I was growing up (though I like to think she came around to jazz and rock later on). Whatever the style, music was very much a thing in the Lucas house of the 70's and 80's.
I bring this up because music often comes up in writing, especially in the fantasy genre. Perhaps it's because Tolkien wove so many songs into The Hobbit, or perhaps it's because music was one of the few forms of entertainment widely available in pre-industrial societies, or perhaps a lot of fantasy authors are simply frustrated bass guitarists (okay, so no one is ever a frustrated bass guitarist, but you get the idea). But having characters sing a song--and then writing out the song's verses--is very much a thing in fantasy fiction, almost a trope.
I was looking back over some of my stuff and realized I've done it a few times myself. My very first novel (a long, middle-grade animal fantasy) has about five different songs the characters sing at various points along their journey. The Mountain has one, too. Yonder & Far: The Lost Lock has a chapter that weaves in and out of a character singing a lament (the lyrics are very loosely based on an Oscar Wilde poem). It's not something I really set out to include, but it does seem to pop up from time to time in what I'm writing.
Music in prose a bit tricky, though. Sometimes the songs that come up in fantasy novels can come off a little flat (pardon the pun). To be honest (and, please Tolkien fans, this is meant as no disrespect, so hold on to your pitchforks and torches), I pretty much glanced past most of the tunes Tolkien ever put in his books (I mean, I could kind of get a feel for the goblin songs in The Hobbit, but it was a little hard to catch the tune of "O! Tril-lil-lil-lolly the valley is jolly! ha! ha!"). In fact, I'll go so far as to say that fashioning music into prose more often ends up as a distraction than an enhancement of the story.
And yet ... music is an important part of life. For a lot of people, music resonates with something deeper, even something divine. So it's only natural that if a writer is crafting a fantasy world, she or he would want to weave music into it in some way. How does one pull it off so that readers are humming to themselves, and not just flipping past pages?
Two things, I think, can help a song in a novel truly sing. First and foremost, the music has to serve the story, not the other way around. Is recounting twelve verses of metered rhyme doing anything to propel the narrative, a conflict, a character arc, in any way? Is it foreshadowing something? Does it serve any purpose in the novel? If the honest answer is not really, then it probably needs to stay out. Second (and perhaps more challenging), is it actually musical? Often what's described in a fantasy novel as a character or a group singing a song comes across as a character or a group reciting a poem. There is a different beat and meter for spoken poetry than sung music (the latter must generally be shorter and punchier than the former). One trick I've found that makes a song in a story more likely to work: sing what you've written. Yeah, that's right, author. You want your reader to read your song? Sing it to them. Whether it's a tune you've made up or one you've heard somewhere, it doesn't matter. Sing your song. What this trick does is it puts what you've written to the musical test--if it can't be sung, it's not a song.
If your story needs a song in it, and if what you've written fits the bill of a singable song, then your reader will be less tempted to breeze past the singing parts, and might just try to sing along with you.