Warren Gatland's preliminary 45-man squad met for the first time this week as they embark on a gruelling training camp.
Gatland's stars will spend the next three weeks being put through their paces at their Vale of Glamorgan base before flying to Poland for two separate boot camps.
And Roberts, who underwent minor knee surgery last month, is ready for a punishing summer as Wales prepare to take on some of the game's most physical sides.
"This is the start of our World Cup our real preparations start now," said 24-year-old Roberts.
"The knee's good, it was getting to the point where I was hobbling around after a game, so I had minor surgery three weeks ago. I should be back to full fitness in a couple of weeks.
"I'm ready to work hard and push myself to limits I've never reached before. Every training session that first game against South Africa will be in the back of my mind."
Wales make the initial trip to Poland on July 2 and return two weeks later before warm-up matches against England twice and Argentina.
Gatland will then reduce his squad to 30 ahead of the global tournament in September.
The Kiwi has already warned his players they will go through pain and agony in Eastern Europe where they will also be exposed to temperatures as low as minus 110 degrees Celsius in cryotherapy sessions to aid muscle recovery.
But the centre who wreaked havoc on the 2009 tour of South Africa is confident Wales will reap the benefits before they take on the Springboks, Fiji, Samoa and Namibia at the World Cup.
"There will be a big emphasis on fitness and I'm really looking forward to Poland, it will give us an opportunity to reach our peak physical condition," added Roberts.
"We've done it before and it was really beneficial, it's also a good laugh and will be good for team bonding.
"It's the ultimate to represent your country at the World cup but it's important that we go there in good shape."