What do you do to develop/mantain/enhance proper discipline?

I would consider myself a smart 20+ yo guy and I can tell for sure I am extremely passionate about learning as much as possible (IT related mostly). I have achieved very good professional results in the past 8-10 years. However I am struggling for as long as I know myself with discipline, forming and holding on to good habits. At least for me its frustrating noticing how much time I waste doing random things instead of improving my knowledge or myself in general. Although I quit social media long time ago, there is always some ALT+TAB thing to get me distracted.

What are you thoughts on this, what did you try, how did you build good habits, how do you maintain consistency (heh)?

Probably some of you will say that you should start slowly with something and things will compound. I kinda tried that, went to gym regularly, eat regularly, tried to learn every day in the same time interval ... all good until some unexpected things repeatedly break the pattern and I loose my motivation / discipline very fast (it even happened with the gym as I had to miss it for 3-4 weeks due to a medical condition; I never went back, it's been ~3 months now).

Curious on all ideas, tools, tricks!

Thank you!