I know exactly where you’re coming from having been there myself and currently coaching the missus through a similar stage.
It’s a combination of many of the things above – better sleep, resting properly between exercise, improving diet, less alcohol etc, but I think one of the most important is being kind to yourself and don’t expect too much, too soon.
It will take time, but set yourself a series of small, achievable goals. No matter how small, when you achieve them give yourself a pat on the back or a small reward/treat. Also, don’t be afraid to say “no” to other people when they’re asking for your time or putting demands on you.
There’s no one size fits all solution, but the fact that you’ve recognised it and want to change things is a good place to start. Good luck!