Son Doesn’t Want to Participate in Activity

My son told me he doesn’t want to go to his summer morning sports activity. I worry that he needs the physical activity and the opportunity to interact socially, but he says it’s boring and he doesn’t know anyone. He went to camp last week and didn’t complain once, even though he didn’t know any of the other kids at the onset of the week. Should I make him keep going to the sports activity or respect his wishes?