Murray, the world number one, will meet Swiss third seed Wawrinka in the opening match on Philippe Chatrier Court at 11:45 BST.
It is a repeat of last year's semi-final, which Murray won before going on to lose in the final.
"Sometimes you just have to do what you have to do to win," said the Scot.
"It's not always about how well you play or the level that you play at."
Spain's nine-time champion Rafael Nadal will play Austrian eighth seed Dominic Thiem in the second semi-final.
Murray, 30, arrived in Paris short of wins after a season interrupted by illness and injury, but has found his form over the course of five matches at Roland Garros.
However, the other three semi-finalists are yet to drop a set, while Murray has lost three so far.
"They are all obviously playing extremely well," said Murray.
"Rafa's had a great clay-court season, as has Thiem. Stan, this tournament, has played great. He won in Geneva [before Paris] so is obviously confident.
"I came in playing garbage. I'm the odd one out in the semis, but hopefully I can keep it up."
It will be the 18th time Murray has played Wawrinka, with the Briton having won both last year's meetings at the French Open and ATP Finals.
An added dimension to the contest is the fact that both men have won three Grand Slam titles, with Murray yet to win in Australia and France, and Wawrinka missing a Wimbledon victory.
The Swiss, 32, has won majors in each of the last three years and has been in scintillating form, hitting as many forehand winners (70) as Murray in three fewer sets, and six more aces at 30.
"Hopefully a different result," was Wawrinka's response when asked to look ahead to a repeat of last year's semi-final.
"That's what I expect and I hope.
"I think he's probably a bit less confident. He's a bit more hesitant. Hopefully I can take advantage of that and find solutions to beat him."
Seven-time Grand Slam champion John McEnroe:
"Andy's much tougher to beat in best of five, he's worked so hard on his conditioning.
"He exerted so much energy and effort to get to number one at the end of last year, I wasn't surprised that he tailed off for a while.
"I think he's been pointing towards the French for quite a while and he's acting like the player that we look at and go 'that guy's ranked number one in the world right now.'
"You've got to live up to it."
Former Wimbledon champion Pat Cash:
"I think Andy's done really well. Grand Slams excite him. He puts the hard work in throughout the year.
"Stan's the guy who's a danger to everybody.
"Once he gets rolling he can just hit winner after winner and nobody can do anything about it, nobody can stop him.
"It doesn't matter who you are, including Rafa."

Helicopters involved in Nato's Joint Warrior exercise have landed at RAF St Athan.
Parachute regiment 2 Para Battle Group will practice assaults at training areas in Caerwent, Monmouthshire and Pembrey, Carmarthenshire.
In total, around 13,000 NATO personnel from 14 countries are taking part.
Britain's Andy Murray will try and "find a way to get the win" when he takes on in-form Stan Wawrinka in the French Open semi-finals on Friday.
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Around 1,500 troops have converged on the Vale of Glamorgan in what is believed to be one of the largest military exercises held in Wales.