The Real Madrid man said: "I feel good, I'm healthy and most importantly I have had the right training.
"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 failed to qualify for South Africa 2010 before exiting the European Championships at the group stage two years later.
However Modric, who has 75 international caps, believes his country can impress at Fifa's flagship event.
"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," concluded the former Tottenham playmaker.