Boucher, capped 76 times, has not figured in the series after being left out of the first Test in favour of Thamo Tsolekile and subsequently AB de Villiers.
The 28-year-old, also dropped for last year's tour of India, was named in South Africa's squad for the fourth of the five-Test series at the Wanderers.
"I was prepared to work for a long time -- a couple of years -- to get back into the team, so it was a big surprise to get back at this stage. But I guess the selectors looked at my experience and felt they needed it," Boucher told reporters on Tuesday.
"In a way it will be like my debut all over again, except it's more exciting. I feel like a youngster again."
Boucher, who is approaching 3000 Test runs, said he was sure when the 20-year-old de Villiers came into the side that his chances of playing in the current series had gone.
"I rate AB as a serious player with a lot of talent and flair and when he kept wicket I started to feel dropped and out of the loop," Boucher said. "It was tough watching the guys playing while I was on the beach."
Boucher and De Villiers are likely to play in the fourth Test.
"I know what it takes to perform at international level and I can lift my game when necessary," he said. "I feel in form, I'm hitting the ball well and I've had lots of starts -- 40s and 60s -- in domestic cricket."
Boucher said he did not believe some reports that he had been dropped because he had become complacent and a poor influence in the dressing room.
"There was no way I ever put on that South African cap and felt complacent and everything was fine in the dressing room as far as I was concerned.
"I think first and foremost the reason I was dropped was a question of form. Starting with a bad tour to New Zealand, I was not performing with the bat, although I felt my wicketkeeping was pretty good.
"I've had time to reflect and change the way I look at cricket. I'm also going to try and bat more for time and not play so many shots."