I would caution against calling it depression, which is a set of symptoms classified as a disease and really can only be evaluated by a professional.

However, I recently went through a period of anhedonia (https://en.wikipedia.org/wiki/Anhedonia), which may be what OP is experiencing.

Things that I found that worked: exercise for pleasure (riding my bike!). Connecting with people (one-on-one -- i'd always been part of a big group before). Learning new things, new challenges. Yoga.

A book that helped me a lot was Frankl's "A man's search for meaning". I realized that I had a bit of fight club nihilism in me because I never chose my purpose in life, and so was just sitting on the metaphorical treadmill of existentialistic wallowing.