Check for your standard rut-inducers
If you were perpetually exhausted, and you went to the doctor, she'd asses for various nutrient deficiencies. How's your iron? Your thyroid? Your adrenals? Your sleep?
Psychological ruts aren't much different. If you're deprived of social connection, mood-boosting nutrients, fun, purpose, and so on, well, that’s a recipe for a rut.
Ask yourself the following questions to sniff out common culprits:
How's your social connection? Do you work a job where you feel connected to your colleagues? Are most evenings spent solo? Does a weekend go by where your most significant interactions are with the Seamless delivery guy?
When's the last time you had fun? Like, legit fun, where you forgot about the world and just enjoyed yourself?
When's the last time you got your endorphins pumping?