Everyone can sense energy it's just that some are more energy sentitive then others. When you start working with energy your body will get used to sensing it so the more spells you use the more psi balls you make etc you will get better at sensing energy. Some people can barely feel any energy at all well others are hyper energy sentitive and can sense the smallest differences in different energies. Majority of people are either average or little above or below average when it comes to sensing energy. In my experiences I have found to be hyper energy sentitive you are born that way and can sense the energy around you with out even wanting to.