Daniel Ricciardo has described his 2018 season in Formula One as "mentally testing" but is hopeful that the experience can make him "stronger".
Ricciardo's impressive beginning to the season seen him emerge as an early title contender with Red Bull Racing.
However, the Aussie had a number of reliability issues with Red Bull's Renault engine and it resulted in Ricciardo having eight DNFs in 2018 - more than any other driver on the grid.
Ricciardo announced during the summer break that he'd be ending his tenure at Red Bull Racing and make a rather surpising move to Renault for the 2019 season.
The new Renault man was asked if 2018 was the hardest of his career, and replied: "One hundrer per cent, yes. Absolutely! Even purely on the results, but then with everything else on top of that.
"There's the contract stuff, the high of Monaco, the low of the DNFs - it's been by far the most intense and challenging season I'ce ever experienced. Mentally it has tested me, but I feel it's only going to make me stronger down the track."
Ricciardo singled out his win at the China Grand Prix, with his season proving to be like a "rollercoaster".
"I think it sums up the rollercoaster of the year it has been," Ricciardo added to Crash.net. "All the highs and lows, frustration and joy into one. I remember on the podium on Sunday, I was holding in a lot of my emotion because it just plays with you. It does.
"But then, to come out of that weekend, I wasn't just proud of what I'd achieved, I was very proud of the team and proud of everyone who helped me get to that point on Sunday afternoon.
"Also, I heard that the move to the lead of the race was voted overtake of the year, or something like that. So that's pretty cool. Big weekend, for sure."