Tendulkar's retirement has been a topic of debate for quite some time now and the batting great said though he does not have any immediate plans, the thought of retirement has been on his mind.
He said that taking a decision on retirement after playing the game for close to 23 years will be a "hard one" and he will go by what his heart says.
"The moment of retirement is going to be hard because I haven't experienced anything close to what I might go through when I retire. It depends on what my heart tells me then. I need not take a call right now. When I play in November, I will reassess things," he said.
"I am 39 and I don't think I have plenty of cricket left in me. But it depends on my frame of mind and my physical ability to deliver. When I feel that I am not delivering what is needed, and then I will re-look at the scheme of things. I am already 39 and no one expects me to go on playing forever," Tendulkar told a private channel.
India play a four-match home Test series against England starting on November 15 in Ahmedabad.
Tendulkar, who holds almost all the records in world cricket after playing 190 Tests and 463 ODIs, said that it would be a tough call for him to hang his bat and he will go by what his heart says.
"I don't know. It is going to be hard because I haven't experienced anything close to what I might go through when I retire. I cannot relate this moment with any other moment in my life. It will be a tough call. I will go with what my heart says," said Tendulkar, who has scored 15,533 in Tests and 18,426 runs in ODIs.
"But I am still the best judge of what happens to my mind and body. When I feel it is time, I will take a call. It is going to be a tough call nevertheless. It is going to be tough because this is what I have been doing all my life. It is going to be difficult to suddenly hang my boots one day," Tendulkar said.
The champion batsman also said he has been thinking about the moment of retirement for some time.
"Of course, I have been (thinking about it). I am 39 plus and it is not abnormal for me to think of it. At that moment, I will go by what my heart says. At this moment, my heart says I am okay. But you will have to look at series by series."
One of his most cherished dreams was realised last year when India won the 50-over World Cup. Asked if he was game for competing in the 2015 edition, Tendulkar ruled out the possibility.
"At this stage, I don't think it is possible. I am being very honest and straightforward. I am going series by series because it is also about what the team feels and what I feel inside...whether I have the motivation to continue," he said.
Asked if he was pushing himself too hard to stay competitive and in top form at this stage of career, Tendulkar said, "I have always been pushing myself, for the last 22 years and more, to play for India. It had always been a dream.
There is no reason why I should not be pushing myself too hard. In fact, if I don't, then you should question me on why I am not pushing myself hard enough.
"When you play for India, you are playing a team sport. The team to move in the direction that the team wants you to move in. Everyone is striving to achieve something unique. Especially because it is a matter of pride and honour to play for India.
"Playing cricket for India is something I am not willing to make a compromise on. The day I stop playing, I do not want to feel that I did not give it my best shot," he added.
Tendulkar, however, refused to give a specific time frame for his retirement.
"Nobody decides in this manner. I do not know what is in store. I wish I knew. If I did know, I wouldn't have had to wait for 22 years to lift the World Cup. Perhaps, I would have done it in the first instance in Australia in 91-92 then.
"I am looking at it series by series. As long as I feel that I can deliver, I will continue playing. It also depends on what the team feels and whether I am motivated enough to continue being on top of the game."
Asked if his retirement would be from all forms of the game, he said, "It again depends on what my heart tells me then. I need not take a call right now."
Sunil Gavaskar had suggested that age has caught up with Tendulkar after he was bowled thrice in the recent home Test series against New Zealand, but he conceded that it was natural for others to raise such questions.
"Sunil Gavaskar has also said positive things about me. When there have been a lot of positive feedback as well, why keep harping only on the negative comments?" he asked.
"Ultimately, if I am out, I am out. I can't get stuck on one article about me and try to create something that the person is hoping to create out of it. I need to stay focused on the game and constantly keep finding ways to improve myself," he said.
"There are two different things - scoring runs and what I feel. For instance, if this three-wicket ordeal had happened when I was 25, no one would have questioned it. Incidentally, it happened when I am 39, so questions were raised. This is natural," he added.
Asked about another former captain Mohammed Azharuddin's comments that his reflexes have slowed down with age, Tendulkar said, "When I met Sir Don Bradman in 1998-99 on his 90th birthday, he told me that it is natural for a batsman to change after he is 30. I have played quite well for nine years after I turned 30. It is natural for any person to slow down as he grows older."
Tendulkar said he stays away from opinion of others about him to avoid getting affected.
"I have always stayed away from what people say about me, right from my younger days. My brother always told me that I need to keep away from all this to stay focused on the game. Irrespective of criticisms or praises that come your way, it is important to stay focused and keep improving your game."