How do you guys deal with little to no motivation?

I'm constantly lethargic with zero motivation to do anything apart from stay in the house. I can barely make it to work even though I only work 3 days per week. I also miss basically every class and lecture because I physically can't get out of bed or go to bed at the right time to make the class.

I know the advice will be something like 'Just man up and do it' but it's actually not physically possible. I'm in a massive slump and have depressive thoughts almost constantly.

What should I do? See a doctor? Not sure how to go forward from here as I've been like this for 2 years and don't see it ending without a massive intervention.