The 23-year-old has suffered from an ankle injury for the past few years and has often been forced to play through the pain barrier.
However, Riviere has begun the Ligue 1 campaign with five goals in four games and believes that his form is down to the club's doctors.
"I don't know whether you can say that things have just fallen into place for me," Riviere told reporters. "It has been two years since I had a complete [pre-season].
"The doctors and physiotherapists here at Monaco have managed to fix my ankle, which has handicapped me for two years.
"Thanks to God, everything is going well now. I'm at 100% of my capacities, which is essential given the way I play."
League leaders Monaco host Lorient at the Stade Louis II on Sunday.