American spiritual teacher Adyashanti writes in his article “Bliss in a By-Product” in the Summer 2009 issue of Tricycle: The Buddhist Review:

We must give up the pursuit of positive emotional states through spiritual practice. The path of awakening in not about positive emotions. On the contrary, enlightenment may not be easy or positive at all. It is easy to have our illusions crushed. It is not easy to let go of long-held perceptions. We may experience great resistance to seeing through even those illusions that cause us a great amount of pain.