If you want to be a car racer then you need to be as fit as you can be. Though, it is not a requirement, a fit body would ensure that you can last long in the race track. If you don't think that this is a requirement then try driving any kind of vehicle all day and you would see how tiring it could be. On top of that, race track drivers drives some of the fastest cars in their country. It is harder to control a car that is fast compared to a normal car. If you think that driving a normal car all day is already tiring then wait till you try driving a race car.
Once the signal is given, drive as fast as you can till you reach the finish line for the fifth and last time. Don't think that this would be easy just because you have driven some car games before. A racing game is different since there would be other car that would compete against you. The other cars won't hesitate to leave you if you are too slow. You need to win the race if you want to race in the next stage. If you can't do that then you would race again in that stage.