The movie begins with Siddharth (Shah Rukh Khan), a successful advertising executive who appears to have it all - a beautiful girlfriend, Naina (Preity Zinta), and a promising career. However, he's diagnosed with a terminal illness, which sets him on a path of self-discovery and introspection. He befriends Aman (Hrithik Roshan), a charming and carefree young man, and together they embark on a journey that changes their lives forever.