I'm a Chinese who continued to learn English after college and now I use English as my working language. My learning is that one shall match his personal interest/career need to his foreign language learning. You can choose the foreign language materials that interest you, what you've learned on these subjects in the foreign language will fuel your interest to study further and because what you've just learned are stored in the excited zones of your brain, there is more chance to repeat what you've learned and enforce it consciously or unconsciously.