Read "Driven to distraction" https://www.amazon.com/Driven-Distraction-Revised-Recognizin..., you may resonate with some of these points (even if you don't experience a full-blown ADHD).

In my case, well, if something really needs to be regular, the only way to go is external pressure (external deadlines, people meeting at a given time with the goal to learn) and bringing some intensity (instead of 1h learning, a day focused on that).