Children who live in cities aren't getting as much exercise as they should, a report has found.
Lots of the kids questioned admitted they played computer games and watched TV for up to four hours a day, but rarely did anything active.
Many kids in cities don't walk to school and don't do any exercise in break times.
This is worrying because if you don't do enough exercise it can make you obese or ill when you get older.
Girls appeared to be less active than boys, with only about one in 10 saying they did any kind of exercise at lunchtime.
Children from south Asian backgrounds were also less likely to do enough exercise, the report showed.
People from a charity called the British Heart Foundation, which carried out the study, said the results were "alarming" and that more should be done to get kids to be active.