When I first started, my right arm would fall asleep and I'd sweat like hell. The first day, after 31 minutes I collapsed forward, my legs fast asleep, I had to crawl forward and turn over. Then as I lay there, I got the chills, even covered with a blanket. After some practice though I began to notice great things.
It's never really about removing negative energy, but rather raising the vibration of the energy that is there. Keep adding light as it were. When you shine light on a shadow it also becomes light.