I think your biggest issue is how much you're working (and not sleeping). I'm a successful, reasonably good programmer in my 40's. In my whole life, if I didn'

I think your biggest issue is how much you're working (and not sleeping). I'm a successful, reasonably good programmer in my 40's. In my whole life, if I didn't get enough sleep, or did too much overtime, my ability to reason and my productivity fell off a cliff. And I'm talking about, working the occasional extra day or few hours. It's the same with sleep too - if I don't have enough sleep, even for one night, the next day I'll be way, way less capable. You have to fix this first before you'll be able to do anything else. Fatigue and lack of sleep will interfere with any attempts to improve your programming skills (LeetCode or otherwise); it will bring down your interview performance; it will hurt your self-esteem and motivation and general energy levels (and health!). You don't necessarily need to resign. I would talk to your employer and insist that you need to return to working regular hours (40h/week maximum), and that they find people to take shifts with you for the on-call stuff. If they don't agree to this though, I would quit. Plan your exit so you have enough savings to cover a few months off. I don't think you need to go on a big vacation or go traveling or anything like that. But what you do need is enough time to rest and recover, properly catch up on sleep (this can take a month or more!), do some exercise, maybe pick up a hobby. Then only once you feel rested, look for a new job. The good news is you're in your 20's. Your body and mind are resilient and will recover given time. Once you're rested again, you'll find learning, improving your programming skills, or even the dreaded LeetCode will be much more doable. Also some advice from someone in their 40's: software engineering is a very deep and broad discipline. There is so much to learn; you're just getting started. Give yourself time! (Can be difficult advice to follow when you're young). You have lots and lots of runway to learn, practice your craft, absorb knowledge from others. I wish you the best! :)