Marcus Trescothick admits he fears for his England future after ruling himself out of the winter tours to Sri Lanka, South Africa and New Zealand.
Trescothick has refused to put a time-scale on his recovery
The 31-year-old has not played international cricket in almost a year because of a stress-related illness.
And Trescothick told BBC Sport: "I can't control when the selectors will say enough is enough. I know the longer I leave it the more likely that gets.
"But all I can do is try to get myself right. The time is just not right now."
Trescothick, who was dismissed for 18 while batting for Somerset against Derbyshire on Wednesday, has twice had to leave England tours because of his illness, most recently ahead of the Ashes series in Australia last winter.
And, despite originally making himself available for selection in the 30-man squad for the inaugural World Twenty20 competition in South Africa later this year, the opener says he is still unfit for internationals.
"I can't go into details as it's quite a personal thing," he said, "but I'm working with different people, trying to address problems that have happened in the past and trying to move on and find ways of coping with times when I don't feel so good.
"I can only control what's important to me and that's making sure I get back fit enough to give myself a chance of coming back and being as good and better than I was before.
"Of course it is frustrating watching the boys go out in Tests and one-dayers without me but, while I'm still playing well and on the right road to recovery, I'll believe I can come back."
Trescothick has not pulled on an England jersey in almost a year
The selectors and management team are prepared to give him as much time as he needs to recover, even though he will not be available now until next summer at the earliest.
"The selectors have been acutely conscious that it would be counter-productive to try to rush Marcus back into international action before he was ready," said chairman of selectors David Graveney.
"We appreciate the fact that Marcus has alerted us at the earliest opportunity of his decision which will avoid there being any disruption to the team's one-day planning processes.
"Marcus has proved himself to be a very special talent on the international stage and we look forward to his making himself available again for England when the time is right and to his pushing his case for selection through his performances for Somerset."
Trescothick has played 76 Tests and 123 one-day internationals since making his debut seven years ago, and scored more than 10,000 runs.
His illness first manifested itself in India last year, and he later opted not to return to the sub-continent for the ICC Champions Trophy.
He is still relatively young for an international batsman and we believe that he has many more years playing
Somerset director of cricket Brian Rose
The selectors put their faith in his recovery by picking him for the tour to Australia but after playing in the opening two matches, he flew home before the Test series got under way.
Despite the emergence of Alastair Cook, however, Trescothick is still seen as a key member of the national team in both forms of the game.
Somerset director of cricket Brian Rose, a former England batsman, said Trescothick had made "terrific progress" with them this summer.
But he added: "His longer team future remains the primary concern for us all.
"He is still relatively young for an international batsman and we believe that he has many more years playing at club and international level."
England's final squad for the ICC World Twenty20 has to be named by 11 August.