Addiction, sugar, bad sleep, medication, behavioural addictions such as gaming and pornography can cause this because they reduce dopamine sensitivity in the brain over-time, same as the other culprits.Alcohol, caffeine and bad food in general.
Could be very psychological also. I would suggest from the tone of your post, you are having a lot of anxiety with this issue. It's important to notice where your anxiety is coming from, for example, if you are telling yourself you 'have to practise yoga daily' then that is a demand you are placing on yourself, Yoga is good for you, but demanding yourself to practise yoga, and this and that, regardless of whether you are actually doing them is not healthy, which in itself causes more anxiety, then you 'check' yourself for your mind-state and the cycle repeats.. Sounds like a vicious cycle, I used to have something very similar. Getting yourself away from thinking about it is the first thing. Stop looking it up.
Concentrate on being healthy and exercising etc, but make CBT the priority and aim to be doing it at all times. Stop those thoughts about the sludge, or giving yourself 2 months to get over the sludge feeling, accept it. It is a slow process, and cannot be rushed. I think in order for CBT to work fully, a level of acceptance has to be attained with your current symptoms. Hope this helps.