Go to therapy. If you dont have insurance start reading stuff like this:
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with a large grain of salt and take some of the core points. Any "self help" book is going to have a lot of fluff but the stuff about mindfulness and ways to hold onto positive moments are critical (even it they sound dumb and you 'know' all this already)
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also start to add in different little changes to your life that you can track over time. Talking medium-term additions. Can be something tiny like going for a walk every morning before work without your phone, maybe journaling or reading for 30 minutes a day, or something bigger like adding meditation or volunteering. The long term, as well as the keeping track aspects, will help time pass as your brain adjusts to the new things, change is done by being the person you want to be at every turn you can. Some months you aren't that person at all, some years even. Some days you do one thing that way and the key turns and you start to notice the changes have finally settled. Each right choice you are lucky enough to make enables the next one to be easier. It takes a long time but you just have to start treating your life as a project itself and tinker until you find what fits. It may really just be one tiny thing or 5 years from now you'll find yourself happy in a life you would have found extremely not perfect at the moment.