Really? You sure it's not just you?
I don't know anyone that's had problems if they've really wanted to play. Every futbol / tennis centre has leagues and there's always people looking for people to play in 5 on 5 tournaments at the small canchas. Ciudad Universitaria runs tournaments every semester on regulation sized canchas. The Y runs tennis leagues, and I'm sure futbol leagues as well. If you're not playing it's for a lack of trying, not for a lack of opportunity.