As someone who is not competitive, Friel's book has somewhat limited appeal to me, as well. However, if you can wade through the verbiage, he does make some good points about maintaining a balance between activity and recovery and about how to build up gradually to your cycling peak.
If you want something that is easy-to-read and really works, try the Abs Diet. It's not really a diet book but a lifetime fitness and healthy eating plan. While it doesn't focus on cycling, the core exercise program is really a good one for anybody who rides a bike.
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"Light it up, Popo." --Levi Leipheimer