Cecilia Ng Kam-kuen, of the Hong Kong Federation of Youth Groups, made the comment after a survey revealed that more than a third of Hong Kong students would join 11 or more extra-curricular activities in the coming school term.
The survey, carried out by the group in August, questioned about 1,400 secondary and primary students.
After they return to school, most students will spend their spare time doing sport-related activities. The second most popular category is art, while going to tutorial classes comes third.
About 40 per cent of students said their biggest challenge was not having enough time to rest. They also need to strike a good balance between those activities and schoolwork - their second biggest challenge.
Students were asked to give a score for their stress level, and more than a third of them gave a score of seven to 10. A score of 10 means they are under immense pressure.
Ng says the intention of extra-curricular activities is for students to have a balanced life, and develop themselves in an all-round manner. A too intense schedule, however, will become a burden because school life is already very busy.
"Children should enjoy doing what they really like," says Ng, "but now these activities have become another source of stress."
If students face any difficulties, Ng says, they should ask for help from teachers, social workers or parents.