Work on just ONE thing at a time to build structure. For example, maybe making a rule to be in bed by x time and get up at y time. For me, it's terribly hard to stop whatever I'm hyperfocused on and go to bed. So I have a rule about being in bed by a certain time and getting up at about the same time every day.

Once you get ONE item of structure integrated into your life, try a second item. For me, that is currently putting every time commitment into my phone calendar--even if they repeating commitments like class times. I get more than 50% of the stuff on there, which is a big improvement lol.

I think it's important to focus on just one change at a time. If you try to implement too many new things, it gets crazy overwhelming.