The planet's biggest problems have to do with sustainability, environmental decline, global poverty, disease, conflict and so forth. Really, they're all interconnected - it's one big problem, which is that the way we're doing things can't go on.

Cities offer us powerful leverage on our most stubborn, wasteful practices. Long commutes in our cars, big power bills from our energy-hogging buildings, shopping trips to buy stuff that'll spend a few short months in our homes and long centuries in our landfills.

For carbon-neutral cities, there are things worth talking about in how our consumption patterns can change - sharing goods, etc. - but those are a fraction of the impacts of transportation and building energy use. If we need to choose priority actions, the most important things are to densify, provide transit, and green the buildings.

There are a lot of different ways of building a prosperous society, and some of them use much less energy than others. And it is possible and more practical to talk about rebuilding systems to use much less energy than it is to think about trying to meet greater demands of energy through clean energy alone.

Cynicism is humor in ill health.

Wherever I am, I always do yoga every day. I think it's so important for my physical health in sport.

Miriam Were has made outstanding contributions to public health in the developing world. She brings basic medical services to women and children in East Africa.

I've been very open about my health challenge because I think it's really important to let my constituents know that in spite of the fact that I am still in treatment, nothing about this treatment prevents me from doing my job.