"I've been struggling all season," he told the official Bolton website.
"I was never myself or 100 percent fit right from the start. At least we rectified fitness problems near the end of the season.
"Now I need a good break to make sure that I'm really ready for next season. I've played football almost non-stop for three or four seasons so I have to be strong now and think about myself.
"I've always compromised and tried to sacrifice myself for my country. But it has affected me this season.
"It is a hard decision not to play in games but I'm not the youngest anymore and it's time to put myself first.
"What I am considering are the World Cup games, and I will see if I can just play in one."