Of course, this kind of commitment to learning a language is only worth something if you can use it. This is why I really need to encourage a personal friend to use it, because, although the Lojban people are mostly nice people, often the only thing I have in common with them is that we are both interested in Lojban, it's not like we would be friends otherwise. So I really need to get one of my friends to learn it.
Also, /jbo/ is supposed to be immersion but there is not much to talk about -- you're not going to bother bringing something up if you don't have to because it's such hard work, and is usually met with corrections (from people acting in good faith, of course).
I have just completed a 10 week British Sign Language course and that was easy enough, once a week on Tuesday. I have an okay grasp and confidence that I could learn any language with commitment. The trouble is that I don't know any deaf people, never mind deaf friends so I am finding it difficult being motivated.
I have a friend who at one time was interested in learning Latin with me, like our own little club language (juvenile, yes). But that kind of fun could be applied to Lojban. I just have to get back into contact with him...