The IIT-JEE (Joint Entrance Examination), the examination used to recruit students into these institutions is arguably the most grueling experience for a high school kid anywhere in the world. Thousands of students all over India spend upto two years of their lives doing nothing other than preparing for these exams. There are many side-effects to this phenomenon.
First, these exams are not like the regular school exams which essentially promote rote learning. The problems are designed to make you think. Two years doing nothing but solving physics and maths problems hones your problem-solving ability to a very high degree.
Second, the pressure to succeed is immense and the competition is cut-throat. Anyone who has successfully been through two years of such an ordeal will be able to handle stressful and tense situations a lot better. This kind of a mindset is a natural fit for a lot of careers that these kids will eventually go on to take up, thereby increasing their chances of success.
<flamebait> At this age, an average high school kid in the US or UK is probably having a lot more fun, trying to get drunk or get laid :) (if you go by all those teen-flicks and TV Shows!) </flamebait>
Related Reference : See this Al-Jazeera documentary on a guy who runs an IIT Training school in India's poorest and most lawless province Bihar - http://english.aljazeera.net/programmes/witness/2009/02/2009...