I will start, and then Marilyn might want to chime in here.
Infrastructure is very important, but it's not enough. The old saying, “If you build it, they will come”, is just not true with respect to physical activity. The behaviour change process is much more complicated. Yes, we do have to have opportunities for people to be physically active, but we also need to ensure that they have the skills to be able to enjoy those facilities and the infrastructure and they need to be motivated to be able to use those things. It's a very complex problem to change behaviours.
If you parallel that to smoking, it's the same thing. We didn't just eliminate smoking places or prevent people from smoking in public places. We did that, but we also had to provide training, tax policies, and public education. It needs a full, comprehensive approach. Building solid infrastructure is absolutely necessary, but it's not enough.