You try to master technique, then when it's second nature you use it to express emotion, tell a story or paint a musical picture.
You cannot learn "technique" (in the sense of mechanics) and delay the "expression" for later. Good technique is the art of making the right sound in the right musical context and should be incorporated from the very beginning.
According to Ms Wong, swimming helps improve "Chi", a source of internal energy in your body, which is also relied on when you play the piano. Chi is a rather abstract concept, but from what I understand here it might simply mean a better level of physical fitness, which of course would be of benefit when you play demanding passages.