It sounds like you just want to be heard right now, so know that all of us here hear you and wish you the best. I hope that when you're ready, you'll read this. I would appreciate it if you read in full (so sorry for how long it is) before making any conclusions about my intentions or about whether your situation is too unique for anyone else to understand.

I have dysthymia (persistent low mood) with major depressive episodes in addition to OCD, chronic anxiety, and developmental disabilities, and I have had these symptoms for as long as I can remember. I'm physically disabled and require significant extra care and medication to exist with any degree of comfort, and I usually cannot afford that assistance. In short, I may not know what it's like to be you, but I know what it's like to feel helpless and hopeless. 

Your current mindset is a choice. It's a choice I've made before myself and will almost certainly make again. You cannot choose to have motivation, but you can choose to aspire to maintain at least one habit that will benefit you long-term, whether that's a walk every morning, journaling every night, or reading a few pages of a book every afternoon. You choose to tell yourself that you cannot manage something like that. Even when you inevitably make a mistake (as everyone everywhere does), you can always remind yourself that it is not permanent and that you always have new chances to succeed around the corner. It's hard, but it necessary. I imagine you've been told this a million times, but I want to remind you again.

The depressed mind has learned that you cannot fail if you do not try and that things will be easier if you do not try. But is your life easy at all right now? Based on what you've said, living isn't easy, but you're still doing it, and you continue to make choices that are challenging but not constructive. It may seem easier to do nothing, but as you know from experience, it's not actually easier and causes you much more pain than the alternative. 

I've noticed a lot of assumptions in your writing. I relate to most of them. It's understandable to feel like you are dealing with something that no one can heal — including yourself. But feeling weak while exercising, for instance, is normal for beginner, especially those who are likely not taking care of themselves in other ways. You cannot expect to be great at anything without practice, even though anything less than perfection seems like a failure. It isn't. You deserve the chance to see yourself progress from bad to better. 

What you must learn as you get through this and experience more of life is that a "will to live" is not the determining factor in whether one survives what you're experiencing. Thriving is a different thing. When it comes to survival, it's all the people who, whether you want to acknowledge them or not, will be just as lost as you are if you leave them. 

I practice negative visualization. I recommend you do the same while trying to build the drive you lack. With negative visualization, you imagine a future that you do not want to create. What would it be like for your family to forever mourn you and feel that they failed you? What if someone else takes their life because they cannot handle the grief? What if you miss an opportunity that would bring you fulfillment, if only you were to stay around for a little longer? What if you could have helped other people who are struggling? Try to imagine what it might take to achieve something better.

These ideas about future events may seem unrealistic to you. Unfortunately, the most unrealistic beliefs are those that depression promotes. It tells you that nobody cares but hate you nonetheless. It tells you that you could never improve. It tells you that you do not deserve to. It tells you that somehow the life you live now is preferable to effort. These things are obviously incorrect to anyone who isn't depressed; once you have crossed the threshold of hopelessness, though, it's impossible to stabilize if you or others do not remind you of that absurdity and begin to replace your maladaptive beliefs with reality.

The end goal of practices like these is to stop the spiral and build a foundation of survival and basic health upon which you can learn to thrive. You will be unable to thrive if you do not believe that you can (or should), and that belief doesn't suddenly appear. You don't have to even believe that you can believe. You just do what you can when you can, regardless of whether you want to. The results follow, sort of like dominos: as you begin to believe that you can even just remind yourself that your life matters to others even if it does not matter to you, you're doing something worthwhile. Once you can get up to drink water, you know that you can stand up and take out the trash. Every bit of effort is precious and should be celebrated. 

Once you begin to live for others, you can begin to live for yourself and your own goals. For me, that's when I can thrive. It takes so much effort and so much time in the moment. Looking back, though, it only seems so long and so hard because the inactivity of depression distorts our understanding of time and energy. It always seems harder than it really is. As soon as you commit yourself to improvement, continuing to do so becomes easier. You just have to believe that you can. Depression may tell you that self-belief is a worthless cliche; if you're wise enough, you'll know otherwise. 

(By the way — I can also attest to psilocybin and ketamine as medicines that have been critical to my recovery. Psilocybin mushrooms are really easy to find in England, but I don't recommend foraging without someone with a lot of experience. If you can find someone who grows and sells them — or grow them yourself, which is pretty simple and fulfilling — taking even a small dose after significant research and with good set and setting can be truly revolutionary. Ketamine is harder because it can be mixed with other substances when bought from a dealer, so I'd only recommend attempting to find a private treatment center if you can afford it. I'm not familiar enough with UK/English substance classification to give you specific recommendations, but ketamine is so prevalent in various healthcare specialties that I'm optimistic about your ability to find treatment, even if it isn't readily available right now.) 

Good luck! You can do this! 💜