Something I told my son as he grew up in the catching position, and have told many other since:
Many things in baseball require doing the exact opposite of what your instincts tell you to do.
Your brain must override your instincts, and you have to drill and train to make it do it.
Your instincts tell you to turn your head when a ball hits the dirt, which ironically exposes the neck and bony areas on your limbs to pain and injury. Blocking position of course maximizes the chance the ball hits a protected area of your body and minimizes the risk of getting hurt.
When you fully understand that the instict is natural, but you must override it to AVOID getting hurt, it gets a bit easier. Drills with tennis balls are great. There are many blocking drills you can do.
But I think the process begins with understanding the task at core is to make your rational brain override your instincts. With enough practice, blocking starts to seem instinctual.