Habits are there to keep you doing something even when you’re not motivated. But lack of motivation can still break a habit… Once you get to the point where the keep up the habit no matter what, though, it’s a lot easier to keep going.
For me, aside from using SRS daily for learning kanji/vocabulary (mostly though WaniKani, but also Anki now), a “motivator” to get me into reading was to join a book club here on the forums. Having a weekly schedule with a set number of pages to read, with discussion threads to help learn grammar, helped keep me mostly on track until I reached the point where I can read completely on my own.
From there, I’ve tried various things to see what works best to keep me reading. (Once I start reading, I can easily spend half an hour or longer at it. It’s getting started reading on any given day that can be troublesome.) Thus, for 2021, I’ve aimed to read a minimum of one manga chapter per day. So far, I’ve missed only a couple of days, and some days I get in extra reading.
Edit:
What would you say your current “goals” are? I’ll bet they can be revised into systems.