Discerning your energy from other's.

How to discern your energy from others? I hold people's hands for more that an hour at a time while doing their nails. How do I know if what I'm feeling is mine or not? Why are most client experiences amazing and others I am stressed, making mistakes, missing or dropping things, anxious, easily frustrated or flustered. What is this? How to discern mine from theirs? How to practice feeling my own, and where their emotions begin? How to gain control of the situation? If it isn't mine, how to embrace the duality while holding space for oneness?