you can do, just as long as you dont start mixing up the words.... try to keep a seperate day for learning each language, so that when you are learning one, the other two are at the back of your mind! and perhaps you should try learning different things at the same time, for example, colours from the first language, verb tables from the second and phrases from the third, so you keep it seperate!! hope this makes sense and all the best with your learning :)

impossible is nothing.

Absolutely!! It is completely possible, I know that as a fact. I am learning 5 languages at the same time and continuing to learn korean and german as well, so that is even more. Just so enthusiasm, and try hard, show interest in what you want to learn. It is possible, trust me! ^_-

If you really want it, you will do it, but it requieres a lot of effort.