Being trilingual

I recently completed the Japanese program at my school and started the Chinese one.  I have been forgetting my Japanese at an alarming rate.  Is it possible to learn more than one foreign language in addition to your own or should I give up?

In lots of countries, you're EXPECTED to be trilingual, like a lot of European countries (with the native language, English and another major European language) and some Arab countries like Lebanon with (Arabic, French and English).

Though you could even say many Lebanese are quadri- or even quintilingual, since Levantine Arabic differs significantly from Standard Arabic which they almost HAVE to know, and most of them know Egyptian Arabic as well.

Of course, not everyone reaches/keeps fluency in all these languages, but some do.