the therapy comes from the belief/philosophy that when the body is in harmony with itself ie aligned, the body’s problems will go away.
The “pushing really hard” is the Dr. aligning your bones. I go whenever I feel the need. Personally, I love the feeling afterwards. Some people don’t like the process though; they find it unpleasant.
But the first time I went, after he cracked my neck I felt a huge pressure released that I had stopped noticing was even there because I had gotten so used to it.