The 34-year-old has not featured for the national side since November 2013, but could make his comeback in the friendly against Germany or the World Cup qualifier versus Lithuania after receiving a call up from Gareth Southgate, who is without injured Tottenham striker Harry Kane.
"There were times where I did think 'maybe I am not going to get in'. But that did not stop me from getting my head down, working hard and just hoping that one day I would get an opportunity to represent my country again," Defoe said.
"I never gave up. I was getting a lot of stick from the lads on the [Sunderland] training ground because I still have the England flag on my boots. But I was just hoping I would get the opportunity again and now it has come I am delighted.
"It feels different coming in as one of the senior lads. The first time round, coming in as a youngster, you are like a sponge, you try and take everything from the manager and the players. This time around it is a bit strange. I am a senior lad and I want to try and help the younger lads, but even some of them have experience under their belts, which is important."
The call up will boost Defoe's ambitious hopes of making it to the 2018 World Cup, should England qualify.
"If I do get an opportunity to go to another major tournament it would be a dream," he added.
"Travelling, getting to the hotel, playing the games. It is something I wanted to do as a kid, growing up watching the major players on TV and wanting to emulate them.
"To be lucky enough to have experienced it, you just want it more and more."