Career
Walesi became one of the first Malawian swimmers to compete at the 2004 Summer Olympics in Athens. He qualified for the men"s 50 m freestyle, by receiving a Universality place from FINA in an entry time of 32.08. He challenged seven other swimmers in heat two, including 15-year-old Malique Williams of Antigua and Barbuda.
Walesi failed to advance into the semifinals, as he placed eighty-third overall out of 86 swimmers in the preliminaries.
Yona also coached the Malawi swimmers at the 2008 and 2012 Olympic Games in Beijing and London respectively.