There are at least two kinds of happiness. The first, hedonia, comes from simple pleasures, like eating food and watching TV. The second, eudamoia, comes from being engaged in activity that you find challenging and meaningful.
All the benefits mentioned above (and more) are covered in a wonderful video series by Dr. Rhonda Patrick, where she interviews scientists Dr. Valter Longo, Dr. Satchin Panda, and Dr. Ruth Patterson. I highly recommend that you watch all three of these videos if you’re new to fasting.