At the 1998 Commonwealth Games in Kuala Lumpur, Malaysia, Simmons won the gold medal in the 91 kg heavyweight division with victories over Ghana, Wales, and the Seychelles.

At the 1999 Pan American Games in Winnipeg, Manitoba, Simmons defeated Jamaica in the quarter-finals, USA in the semi-final, and lost to Odlanier Solís of Cuba in the final by a 4-2 score, taking home the silver medal, despite boxing with a broken hand.

[2] As a result of his broken hand suffered while competing at the Pan Am Games, Simmons was unable to participate in the 1999 World Championships that took place two weeks later.

With 16 countries competing, Simmons qualified 1 of only 2 spots by winning a Gold medal in the 91 kg heavyweight division at the 2000 Olympic Qualification tournament in Tijuana, Mexico with victories over Venezuela, Jamaica, and Puerto Rico.

At the 2000 Summer Olympics Simmons defeated Iran's Rouhollah Hosseini in the round of 16 by a score of 11–6, once again suffering a broken hand in this bout.