The term "נפילת רוח" refers to a state of emotional or spiritual depression, a loss of motivation, or feeling downcast. In Jewish thought, maintaining a positive and joyous spirit, especially in serving Hashem, is considered crucial. Nefilat ruach can occur when someone is overwhelmed by feelings of inadequacy, failure, or spiritual stagnation.

Chassidus, particularly in the Tanya (as discussed in chapters 26-31), emphasizes the importance of joy (simcha) in spiritual service. The Alter Rebbe teaches that negative emotions, including nefilat ruach, can be a major obstacle in one's Avodat Hashem (service of G-d). Joy is viewed as a powerful tool to overcome challenges, both spiritual and physical, as it allows a person to connect more deeply with Hashem and His mitzvot.

However, the feeling of nefilat ruach is not entirely negative. It can sometimes serve as a catalyst for personal reflection and teshuvah (repentance), motivating a person to improve themselves. The key is not to remain in that state but to use it as a stepping stone toward growth and spiritual elevation.