Because that isn't real. Biology doesn't work like that. Any "breakthrough" or "miracle" that happened because of supposed meditation/visualization is merely a coincidence or a lie. To be honest, it takes a number of things to medically fix an issue: therapy, medication, surgery AND a mentally stable mind that is willing to persevere and fight. You are going to drive yourself crazy trying to manifest the impossible. And fake healers trying to steal your money will say, "well it's YOUR fault. YOU didn't meditate enough. Now pay me for more sessions so I can help fix you." Instead use that energy on positive thoughts and accepting who you are as a person, flaws and all! Once you don't care what anyone thinks, your fluency will improve.