What, you thought it was easy? I can't tell you how many hours I've spent using programs like Melody Assistant to score, arrange and endlessly tweak songs to get them just the way I want it to sound--and that's basically just a draft!
Yes, making music is just like any other creative practice: it takes time, energy, and often a significant amount of money. The difference between writing music and something like painting, of course, is that songs are much more editable. But it's basically the same process.