Sometimes I tend to switch my attention from the nostrils to the "up and down" of the chest/stomach
It depends on how well I'm breathing (I have serious problem with the nostrils, it can only be 100% fixed in a surgery)
I do prefer the nostrils, however this change is commom everytime it becomes impossible to keep breathing throught them (so I swith to the mounth and focus on the chest)
Is this switch not recommended for any reason, for instance, is this a problem to reach right concentration?