I want to second the advice to write. That helps me a lot. Pick any of your hundreds of interest or articles. Reserve some time for it, lets say one hour. Study / read for 30-40 mins. And then use the rest of the time to write a summary. That is the hard part and forces you to concentrate and really understand the subject. It also clears out a lot of subjects because you will notice much faster what you are really interested in. Ideally blog about it so you have the pressure to write something decent.