Max Verstappen has established himself as one of the most dominant drivers in the history of F1. Since making his debut in sport in 2015, the Dutchman has racked up three world titles via 52 race wins and a total of 96 podiums. While most of it comes from his natural abilities as an ‘elbows out’ driving style, a lot of the credit goes to his father, Jos Verstappen. The former F1 driver has been a key figure in the 26-year-old achieving ultimate glory in F1, despite most people questioning his peculiar methods.

Since his son’s Karting days, Verstappen Sr. has been an active figure in his life, playing the role of mechanic and mentor at the same time. The father built engines for his son’s kart and would drive him for as long as 13 hours at a time to get him to different tracks across Europe. Even if it were a rain-soaked track where others would leave for home, the Verstappens would stay back and practice. Speaking to TIME about the same, the three-time world champion expressed the emotional toll it took on him as a child.

“From a young age, I saw other kids running around, playing, not really thinking about the future. But my dad, he had a plan. And I had to stick to the plan.”

The 26-year-old added his father thought he was sometimes lazy, which led to plenty of arguments between the two. Having once crashed out of the race while trying a risky maneuver, the father and son engaged in an argument before Verstappen Sr. left his son at a gas station for a little while. As people have continuously come forth to show their disagreement with his parenting techniques, Verstappen Sr. has always defended himself by claiming he was never abusive towards his son.

Jos Verstappen stands by his parenting style towards Max Verstappen

Despite always being at the center of heavy criticism for his tough parenting style, Jos [Verstappen] has always taken a defensive stance when talking about it. The same happened when a documentary crew asked the Dutchman about his beliefs, as quoted by Sports Illustrated.

Speaking to the crew, Verstappen Sr. claimed he was hard on his son but was never abusive toward him. He added his tough style came because he wanted his son to reach the top of the F1 world, and most people do not know what it takes to attain that level of success. Apart from the strict training regime and unforgiving nature, one of the most famous instances of Verstappen Sr.’s ruthlessness came when he slapped his son in a karting race while he wore a helmet.

The negative reinforcement worked well, though, as Verstappen Jr. ended up winning the race. In fact, the relentless training stands as the no. 1 cause behind the three-time champion being as unforgiving as he is when driving on the track.