I’m a pretty casual talker in English (my native language), but when I speak Japanese, I really feel the need to use polite forms, even if I do know the casual form as well (I’ve been trying to learn both so I can get more into native materials like mangas, books, movies, shows…).
I don’t mind it right now since I don’t have any Japanese friends, but I truly hope that by the time I feel ready to try to talk to Japanese native speakers and want to make friends, I don’t still feel *so* compelled to only speak politely. Obviously you speak politely at first, but you don’t once you actually make friends with someone.