A mistake that cost me 5 years: Thinking preparation was progress. Reading every book. Taking every course. Planning every detail. Meanwhile, someone dumber than me started badly and figured it out. Preparation feels productive but it's often just fear dressed up as strategy. You learn to swim by getting in the water, not by studying water.
You need boredom. A lot of it. Start by going on walks without music. No stimulation. No distractions of any kind. If you learn to sit with your own thoughts, for long enough, in time they will start serving you. You'll start having ideas once again. You'll start developing an extreme sense of clarity that will shift you into the next stage of your life. All by being bored, which is pretty insane.