The Manchester City winger won his first cap as a late substitute during the 3-1 win over Mexico at Wembley on Monday night.
Now Johnson has one more opportunity in Sunday's clash with Japan in Graz to stake his claim to be on the plane for South Africa as part of Capello's final 23.
The 22-year-old former Middlesbrough player said: "It was fantastic to have my first experience of England. It's what everyone wants to do when they are a kid and I got a few touches.
"The competition for places is fierce. The training has been really sharp with everyone trying to impress the manager and obviously he has a really tough decision to make.
"I've enjoyed every minute of it and hopefully it will continue."
Johnson added: "The squad announcement is very close now. It's just around the corner. We have one more friendly to hopefully try to impress again and we'll see what happens.
"Everyone is fighting for their place and trying extra hard. Now we go back to Austria and we have one more game. I'll give it my all.
"For me it's my first squad. Everything that comes, I'll take, because I'm not used to this kind of thing.
"Every training session, I'll do my best and relax and try not to think about it (the squad announcement).
"There's obviously some people who are going to be disappointed but, you never know, maybe I won't be one of them."
Johnson is happy to play on either flank if called upon by Capello.
He said: "I don't mind playing either side, to be honest. I think they are both similar. If you are a winger you can play on both because it's the same job.
"I've played a lot on the right for City this season, I think I've started every game on the right and I've felt really comfortable out there.
"But I have played on the left all my life and that is comfortable to me as well. I'll play either side."