Johnson insists a job that could earn him about Â£900,000 over the three-and-a-half years of his contract is not about ego or money.
And England's 2003 World Cup-winning captain also admits he feels a degree of trepidation surrounding the task ahead.
Johnson gave his first Twickenham press conference on Friday since his appointment was rubber-stamped by the Rugby Football Union management board.
And while many England supporters will expect immediate success under Johnson's supervision, the 38-year-old knows the road to possible World Cup success in 2011 could prove a long and winding one.
Johnson, who officially takes charge on July 1, said: "I have got my eyes open to this.
"I am not thinking I am going to turn up and it will work straightaway. It is about creating an environment and getting the right people in around the team.
"In the last year or so, I have been thinking about getting back into the game.
"I always knew when I retired from playing that somewhere, some day, somehow, I would get back involved in the game.
"Sometimes, opportunities come up in your life. They did when I was a player - I was very lucky in lots of ways - and I didn't ever want to be sat down in the future, thinking 'if only'.
"No person has ever done any job without making mistakes. But if you have the right intentions, and you are honest, you can live with yourself.
"I have decided to take the opportunity and have a go at it. I will give it my absolute best - it won't be for the lack of trying if it doesn't work.
"It is not an ego-driven or money-driven thing, it is about trying to do a good job.
"Of course there is trepidation - you would be foolish not to have that.
"But it is not a fear of losing my reputation, it is a fear of doing the job badly. I don't want to do the job badly.
"I never got carried away with iconic status. You need to judge yourself, and I know the truth. I was, and definitely am, human - contrary to popular belief.
"I am very happy to let everyone else take the plaudits if it goes well.
"It is about players. We want superstar players on the field who people will look to in this country and say 'aren't they great'. That would be ideal."