"Lack of motivation" is a generally misunderstood symptom of depression. It does not mean that I sit around thinking, "Oh, I’m so depressed; why bother to do shit I don’t want to do anyway." It means not that I lack discipline, but that there is a mental disconnect between my conscious mind, which says I want or need to do X, and the part of my brain which actually initiates activity. It prevents me from doing things I would very much like to do, as well as things I need to do, rather than indicating simply a lack of interest in doing things which are not immediately rewarding.
If you want or need to go somewhere, whether somewhere you’re eagerly looking forward to going, or somewhere routine, or to the dentist for a root canal which you may be much averse to but have nevertheless decided will leave you better off in the long run, and you get in your car, turn the key in the ignition repeatedly, yet the engine sputters but does not engage, this is not an indication that you don’t really want to go anywhere. It’s an indication that something is wrong with the equipment you need to transport you there.
I am fully capable of sitting for hours, thinking periodically, “I need to pee,” then, “I really need to pee,” and eventually, “Damn, I need to pee,” before being able to jump start the part of my brain which engages with the task of getting up and walking the ten feet to the bathroom, and initiates the movement which allows me to do that.
The more complex the task, the harder it can be, because a more complex sequence of actions must be, in some sense, imagined and targeted before the actions necessary to bring them about can be initiated. Most people are unaware that this process even takes place, because in a healthy brain, it occurs swiftly and automatically. In my brain, it does not.
Probably the best description of that particular aspect of depression that I’ve ever read. At least, that’s how it is for me.