I spoke with one of my co-workers at Learning Strategies who has very similar difficulties concentrating. What works for her is to consciously follow her breaths, in and out, while listening to a Paraliminal tape. Or, she counts, "100, 99, 98..." In this way, she is keeping her conscious mind engaged in something so that her mind does not wander. Try this and let us know how it works for you.
She has always believed she has ADD, although has never been formally diagnosed. She finally realized that if she wanted to get things done, study and learn, and get these tapes to work for her, it was her responsibility to make some changes. She knows that she just needs to take some extra steps.
