I already mentioned how I started reading in another thread. (tl;dr: 2 years of Japanese classes then suddenly manga). It took then a few years to move to actual books, with a few attempts here and there. During that time, I kept learning Japanese and read probably around 300 manga volumes? In the other thread, I only mentioned the first successful attempt at reading a full book, but I guess I should also mention that I made regular attempts during the period leading to that point. The most notable one was たのしいムーミン一家 | L18??. I made it to the halfway point when I was around N3, but eventually gave up. After every failed attempt, I would just be depressed and binge random manga series from Bookoff and go back to studying.
So, I guess I just banged my head on the wall until the wall broke.