If you want to write as a career you’ll have to write on days you don’t want to.
You’ll have to write when you aren’t motivated, when you aren’t in the mood, when writing isn’t any fun. Just because writing is something people can have fun doing, doesn’t mean it’s not a challenging and often tiresome career choice.
Just as an engineer or doctor or lawyer who chose to go into they practice because they enjoy it will have days where they wish they could be doing anything but their job, so do writers who write for a living.
And if you’re not trying to write for a living, you don’t… have to write… like, at all. If you aren’t enjoying your hobbies, you don’t have to make yourself do them.
It’s also okay to recognize that you don’t enjoy certain parts of writing, and then push yourself through those parts because you want to finish your book!
Most writers don’t love or find easy every aspect of the writing process. You’re no less a writer just because you really hate throwing together a rough draft but love doing revisions, or because you have fun slapping down the rough draft but every stage you move toward proofreading you’re annoyed with the story more, or because you like creating a wonderful, publishable novel but can’t bring yourself to so much as think about the actual publishing process.