Why does focusing on heart center in Heartfulness cause heavy burden and stress?

My name is Rohan, born on 15th August 1990. I have been trying this new Heartfulness technique, but the second I focus my attention on my heart center, I get this strange, heavy feeling, almost like a burden is settling there. It feels totally unnatural and causes me a lot of stress. Time: 7:20 PM. Location: Delhi. I'm hoping my birth chart can reveal why my innermost being resists this kind of intense, spiritual focus.