At the office I’m a proud member of the unofficial “Green Team”. Our Office Green Team consists of some out-of-the-closet greens, in-the-closet greens, passive greens, gentle greens, you name it.
I’m known as the idealistic, grumpy green who gives co-workers a hard time whenever they wittingly causing harm to the environment.
One act of wastefulness that gets under my skin is when people drink bottled water when there’s an easily accessible tap-water filtration system in our kitchen. I’ve heard many excuses, but few with sound logic (“I can’t be bothered to get a glass from the cupboard”, or “the cup will need to be washed which is more wasteful than the plastic bottle”, or “I’m lazy” etc.) I find the best way to combat infractions against the environment or “eco-fractions” or “greenfractions” is to make it socially unacceptable behaviour. Once upon a time, smoking was the coolest thing to do. Now it’s frowned upon due to a mass movement of social dissension (In North America anyway). There’s no law that’s as powerful an enforcer than mass social dissent. 
Recently, I peered into a co-worker’s garbage container only to find a recyclable plastic bottle. In Canada, consumers are required to separate trash from recyclables, so putting recyclable objects in the trash can is a big no no in my books.