Sarah Doering was a practitioner, teacher, and supporter of Insight Meditation who had a significant impact on the Insight Meditation Society and several related meditation centers. She wrote an article on the five faculties that describes the way that the five faculties support one another. Her description of energy and effort give a good feeling for the kind of balance needed in meditation and spiritual practice in general. You can find her article here: The Five Spiritual Powers
Sean Oakes provides another depiction of the five faculties, with brief sections on each of them. In describing energy and effort, he talks about exploring the balance between being too loose and too tight in our practice using an analogy from the Buddha. You can find his article here: The Five Spiritual Faculties