The Saracens winger is yet to feature on the tour after first being forced to sit out last week's first Test defeat in Durban with a calf injury.
The 28-year-old was then expected to play in the midweek tour match against the Southern Barbarians but was pulled out before kick-off by head coach Stuart Lancaster to keep him fresh for this weekend.
Strettle is now preparing to win his 12th cap after being named in the side to face the Springboks in the second Test in Johannesburg.
He said: "Last week there was the disappointment of not being on the pitch, but you accept it and get behind the boys.
"You know next week is another opportunity - rugby is a one-week sport, things chop and change.
"It was just a bit unfortunate. I took a bang to the calf and I tried training when I wasn't 100% and it just made it a bit worse.
"But that's in the past now and I am really buzzing about this weekend."
Strettle had been looking forward to a possible midweek run out in Kimberley, and a chance to prove his fitness in match conditions, but Lancaster felt he was in good enough shape.
With changes to the Test team necessary after injuries to Brad Barritt and Mike Brown and with Ugo Monye doubtful, Lancaster did not want to take any more risks.
Strettle said: "Lanny spoke to us on Tuesday and said he would probably pull me out of the game.
"It would have been nice to have had a run around on Wednesday but I will happily miss that game to play at the weekend."
Strettle, who missed just one of this season's RBS 6 Nations games, does not actually know if he would have played last week had he been fit.
Lancaster moved Ben Foden from full-back to the wing in order to play the in-form Brown at the back and utilise the aerial prowess of both players.
That experiment has now been abandoned with Brown sent home for a thumb operation.
Strettle said: "There are players who can play wing, centre and full-back. You know there is versatility there.
"I never spoke to Stuart about what would have been the call if I had been fit, but you know with him if you play well you will get a chance, and that's all any player can ask for.
"It's a changed back line now and we're excited about it. It's going to be one hell of an occasion.
"Every time you pull on the England jersey is a great opportunity and a great privilege. To do it in South Africa at Ellis Park is even better."
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