1. Knowing that I'll always feel this way and always have a need to do something meaningful. It's my life and I get to decide what's important. This might not sound like much but just cementing that I don't need to change has helped me get through bad days.
2. Starting to make a career change. I'm going to try to get into med school, and to get healthcare experience I've just recently completed an EMT certification. I absolutely loved this class. Such a diverse group of people all from different backgrounds who also just want to have direct impact on someone's health. My therapist says I sound like a totally different person when I talk about how EMT is going. I think about that a lot. Last week I got to help a stranger with heat exhaustion and she was incredibly thankful, I think about that a lot too. Just starting to take the first steps towards something more fulfilling has been huge towards giving me something to wake up excited about.
3. I now treat my CRUD app office job like how most people would treat selling stuff on Craigslist - I do not care about it beyond the paycheck. I don't think about how it should provide any fulfillment. I don't think about being here a year from now, or even a month from now. It won't matter in the long run.
Possibly some of these things can be applied to your life as well. Hope this helps.
We are lucky that tech pays so well that we could, in theory, retire early. It is very difficult to keep that in mind when you're miserable at work though...