"He wanted to push himself to the limit." This is how mentor and friend Phillip Kekana of VW Advanced Driving described former rally champion Gugu Zulu.Zulu, 38, died early Monday morning after experiencing breathing problems while climbing Mount Kilimanjaro.He was with the Trek4Mandela initiative as a part of Mandela Day activities. Zulu's wife, Letshego, was also with the expedition.Kekana said he knew Zulu from when he was first getting involved in racing and had recruited him into the iSonto Development project. "It was 1989 or 1990 and I was one of the instructors and managed to find guys from the township [Diepkloof] and Gugu was one of the guys."He used to speak to me often about the things he wanted to do. He was always pushing for more."Known as "the fastest brother in Africa", Zulu became a professional racing driver in 1999.In 2005 he became a presenter for show Car Torque and featured as a stunt driver in the movie Lord of War, starring Nicolas Cage. Nelson Mandela Foundation spokesman Sello Hatang said he was devastated by Zulu's passing."I recruited him to climb Kilimanjaro. The last thing he said to me before he left was that he wanted to speak about doing other Mandela Day projects," he said.Yesterday project leader for the expedition, Richard Mabaso, said Letshego had kept a constant eye on Zulu after he fell ill. "She was with him all the time. She put a pillow under his head to make sure he was more comfortable. It's devastating," Mabaso said.Zulu's navigator for seven years, Carl Peskim, said they were friends on and off the track."I last spoke to him early last week. He was in high spirits and looking forward to his adventure."Gugu Zulu's wife 'at his side for his final moments'The founder of the Imbumba Foundation has described the final moments of Gugu Zulu's life, saying his wife Letshego 'did everything for him' in his final moments. Peskim said Zulu' s death was a shock. "It was surprising because he was fit and health-conscious."Annalé van Rensburg of Climbing Kilimanjaro, said conquering the mountain required coping with the change of altitude, which helps in curbing acute mountain sickness."It can become severe, causing breathing problems. If it is not picked up it can be fatal," she said.- Additional reporting by Deneesha Pillay, TMG Digital and Reuters..