Tolerance.

The tolerance is the capability of being there wether it is pleasant of unpleasant sensation. just the capacity to sit through all the experiences of all kind. You can just continiously act in accordance of some principles.

The daily unit is perfect example of it. if sleep comes sleep, if mind is disturbed, confused, attached then let it be disturbed, confused and so forth but act based on the principles that you have chosen. That is meditation.

Your daily meditation practice strengthen it.

The challenge is the way mind is acting upon the mind. A kind of prepatual cycle.