The midfielder says he is feeling strong after taking a break following his Champions League success with Real Madrid and has called on his side to prove their progress
Creative midfielder Modric, along with Barcelona-bound Ivan Rakitic, is one of head coach Niko Kovac's most pivotal players and was granted additional time to rest prior to pre-tournament training.
However, after a gruelling campaign with Real Madrid, where Modric won the Champions League and the Copa del Rey, he insists he is fully fit going into the World Cup.
"I feel good, I'm healthy and most importantly I have had the right training," he said.
"I got a few days of rest after winning the Champions League and the chance to mentally switch focus to the team.
"I am ready, eager and cannot wait for the first game of the World Cup."
Croatia missed out on the World Cup in South Africa four years ago before bowing out of Euro 2012 at the group stage.
However, with the likes of Modric, Rakitic and Mario Mandzukic all in good form, Kovac's side stand a good chance of making it to the knockout stages - despite only scraping into the finals at the expense of Iceland in the play-offs.
"As individuals, we have made a huge step forward and we will see in this tournament how we have progressed as a team," Modric added.
"We played very well at the European Championships two years ago but we lacked a little bit of luck.
"Then we had a lot of problems in qualifying. But I think that in this World Cup we could go far and our first goal is to get to the second round."