DWAYNE 'THE ROCK' JOHNSON wants to ''elevate'' movie franchises he joins.

The actor - who is set to star in the upcoming 'G.I. Joe: The Rise of Cobra' sequel, 'G.I. Joe: Retaliation' - has been hailed as ''franchise Viagra'' after helping boost several film sagas, including 'Fast and Furious' and 'G.I. Joe', but he insists he will only join an existing franchise if he believes he can add something extra to the series.

Speaking at the 'G.I. Joe: Retaliation' press conference in London earlier this week, he said: ''It's interesting being involved in all of the different franchises starting with 'Fast & Furious', 'Journey 2: The Mysterious Island' and 'G.I. Joe'. The goal with being involved in franchises is just, when I look at the script with the whole team, the studio - if there is a way I can come in and elevate it [we'll do it].''

The wrestler-turned-actor is one of the most in demand stars in Hollywood today, appearing in several big releases this summer - including the latest 'G.I. Joe' movie, 'Fast & Furious 6', Michael Bay's 'Pain and Gain' and drama 'Snitch' - and he is also training for his next big screen role, 'Hercules', and a main event wrestling match at WWE's 'WrestleMania 29' pay per view next month.

Johnson admitted it's a ''delicate balance'' juggling his hectic workload.

He said: ''It's a very unique time, it's a fun time and what makes it fun for me and audiences, I think, is that it's kind of a D.J. buffet happening. Whatever you want, you can get that between the movies I have coming out.

''It's a fun time and it's a challenging time, too. Any time you have a movie coming out, of course you've got to promote [them], and they're really good movies. I'm also preparing for 'WrestleMania' and preparing for 'Hercules' at the same time. It's a delicate balance of trying to balance the schedule out with all the press and also the prep for 'Hercules' and of course 'WresleMania'.''