Practice. Practice. Practice.
Practice on days when you are thinking about something else or you really don’t want to freestyle. Practice until you get bored with freestyling. Practice until you’re lying on the floor falling asleep. Then keep practicing.
If you’ve been practicing enough, you’ll reach a point where you can freestyle even when you’re distracted, not paying attention, or bored. Imagine doing that when you just started? It’s like saying your name, or walking. You aren’t concentrating on every letter or every move, maybe your thoughts are elsewhere, and you’re still doing it pretty well. You’ve become a decent freestyler even when you’re not trying. Now what can you do when you really give it your best ability?
Prawns calls this his “80% rule.” He doesn’t push for maximum intensity at all times. He strives to push for 80% so that when he really needs to slay it and it really counts, he can push it for that extra 20%. Note that “80%” refers to his energetic effort and not a level of quality. If you can leave some energy in the bank and relax into the flow, you can increase the quality of your freestyle.