There is also a holism in training itself. Try to achieve a balance between races simply for training and those that are important. Get a balance between mileage and enjoyment. Maintain motivation through different types of training and through the endless, year round training. Each person will have to try for this balance in their own training.
Many people find that their dietary preferences change with hard training.
I also, interestingly, tend to eat less. Each person will have different experiences, but it is probably fair to say that your body will dictate your needs. Try and get extra sleep during hard training. Go to bed earlier and rest on weekend afternoons. If your work involves some physical labour then try to limit this when training hard or when preparing for a major race.