Mitchell Johnson will go from pummelling England to pumping iron in a bid to ensure his devastating form carries through to next month’s tour of South Africa.

Johnson says his remarkable comeback this summer has been built on physical strength, and he believes the key to staying on top in 2014 will be the work he can do in the gym in between series.

An improved mental state and bowling technique have also been behind Johnson’s man-of-the-series efforts this Ashes.

But those advancements have all stemmed from the confidence he now takes from his imposing physique.

Johnson has 31 wickets and three man-of-the-match awards this series, and is in the mood to add to his tally in Friday’s fifth Test at the SCG.

After that he’ll feature for Australia in five ODI matches against England, before the Test side heads to South Africa at the end of January for a three-match assignment against the world No.1 Proteas.

In and around the one-dayers Johnson will prepare for another red-ball assault by working on enhancing the intimidation factor which he’s used to overwhelm England.

“One of the big things for me has been to be able to keep my gym work up,” Johnson said.

“(I want to) keep that strength going, keep being around positive people and keep enjoying my cricket. Just staying as fresh as possible mentally and physically.

“We’ve got a little bit more time off this year. So it’s having those times when I’m able to get back home and do the right things back home.

“It’s pretty simple, really. I don’t want to over-complicate it.”

Johnson says the clear direction given to him by captain Michael Clarke and coach Darren Lehmann this summer has been another factor behind his dominance.

“In the past I’ve felt I’ve had to play different roles and sometimes that still happens,” he said.

“But in general my role has been very clear … to go out there, bowl fast, be aggressive, bowl in short spells. I’m very comfortable with that.”

Johnson was outstanding in South Africa back in 2009, taking 16 wickets at 25, but struggled in 2011 as his Test career began to unravel.