Kumbhak is experienced during Yoga Nidra

I have been doing Yog Nidra regularly. Is it ok to change the sankalpa that I am doing since my first Yog Nidra experience? Also during Yog Nidra many times a state is observed when breathing slows down and status of kumbhak is experienced. Mind gets diverted when the capacity to hold breath ends and again it continue to listen into your instructions. Please guide me. Visit http://www.gurumaa.com for more videos