For about ten years now, I've kept a New Words document on my desktop. If you need a further explanation of what that is (well, you shouldn't because it's embarrassingly self-explanatory) - it simply means that every time I come across a word I've never heard before (whether it's from reading something or hearing someone), I write it down in this Word document. And at the end of each month, I look up the meanings and put them all on flashcards so I can carry them around in my purse and go over them in any free daily moments that I have. I eventually throw out each word after I'm completely positive I won't forget its meaning.
I can't tell you how helpful I've found this. And maybe you're the type of person to hear a new word, look up its meaning, hold that information inside you immediately and move on with your life. I should wish to be so lucky. Anyway, it's a good idea if you have a bad memory. Or you just miss the general sense of school-like activities.