Not too difficult. It's never "easy" per se, but I have studied 5 languages and did reasonably well in all of them. High school: 1 year of Japanese and 4 of French. College: 2 semesters each of German, Spanish, then Arabic. I enjoy doing it. It's such an amazing feeling when you can finally understand sentences and so forth; just as I felt when I was a wee lad and could read a book by myself for the first time. It's like reliving that experience.
If I had been wiser I would have stuck to one foreign language, two at the most, and studied them until I was totally fluent. These days I can only speak English. Might have remembered these languages better if had stuck with just one for a longer amount of time.