I heartily recommend this book. I used to be a bit half-hearted with my home training, but it really helps you understand how to use your home training time to improve your fitness and techniques.
It gives you lots of ideas for exercises to sort out any problems and build up your strengths so you can use your training time more effectively.
Mine's really dog-eared and tattered because I refer to it all the time. It's a great motivational tool too. If I'm sitting in front of the TV and can't be bothered training, I just open a page, read a couple of lines and get excited about working on a technique and hey presto, I can't wait to get up and at 'em.
Love it.