The 23-year-old, who has a conditional third spot in the New Zealand Olympic team, was happy with his podium placing in Huatulco.
"I knew it was going to be about survival in the heat and the last 5km of the run was going to be critical," Sissons said.
"I spoke to Kris Gemmell who had done this race a few years ago and he just said be patient and wait. That's pretty much what I did and it worked out.
"I didn't have a great swim but was patient on the bike and we got up to the front pack at the end. I was patient again on the first half of the run and then made my move with two and a half [km] to go on the run and made it stick.
"The legs were hurting on the run, there's no doubt, but there were a lot of guys hurting a lot more than me."
Sissons' silver medal is even more important in that it provides crucial ranking points. With only the top eight nations allocated a third representative for the Olympic Games, New Zealand needs to remain inside the top eight for Sissons to compete in London.
"In Sydney I didn't score any points because I had that crash and was really disappointed.
"Having a great race here was fantastic, and now I move on to San Diego next weekend where I can hopefully make that third Olympic spot a bit safer with another good result."
2012 Huatulco ITU Triathlon World Cup
Elite men results:
Simon De Cuyper (BEL) 02:02:34, 1; Ryan Sissons (NZL) 02:02:50, 2; Danylo Sapunov (UKR) 02:02:54, 3.