I know the sustainability is fun to talk about, and personally I spend the majority of my spare time arguing that sustainable development should be the only kind of development. (Yup, it's definitely not spent on StumbleUpon.) Discussing the concept doesn't explain how it can be implemented. Sustainable industries put as much of a resource back as they extract, so industries like fishing and logging could be sustainable without much difficulty. Resources like energy and transportation are more difficult, while metal extraction will never be sustainable.
The following are my personal favorites. If you have other ideas, post a comment and I'll add it to the list. Unlike many lists online, these result in very little extra cost or effort, and have distinct benefits. More extensive lists are of course useful, but not if you're trying to convince people to start doing anything. I imagine many of you already do most of this, but you can pass this on to some of your friends, and they can pass it on, and all our problems will eventually be solved. =D!
- Replace paper and styrofoam coffee cups with a traveller's mug. It saves a lot of waste, it's more comfortable and keeps your coffee hot longer, and all it requires is washing your mug out afterwards.
- Buy Fair Trade coffee, certified with the most common logo by Transfair, and beware of imitators. Fair trade coffee is just as expensive as normal coffee, but results in much more being given to the farmer rather than to some giant wholesaler. Coffee is not a high-value product, since it can be grown in many places, and so by buying Fair Trade you are supporting some of the most disadvantaged communities in the world, rather than the wholesaler who gets all of the profit from normal coffee.
- Bike. You've probably been told not to drive your car a zillion times, but biking is the best way to get around within a city. There are huge benefits, but you do have to accept the risk of falling or getting hit by a car if they're pulling out and don't notice you. I don't have hard statistics, but driving is probably more fatal than biking and biking probably has a higher risk of injury, so it's certainly not more dangerous. And it's way better for you.
- Buy local food, usually from markets: it's the best food you can find in a city. The food is way tastier and more varied than what supermarkets have to offer. At Safeway, you can get a soggy red tomato. At the Granville Island market in Vancouver, one stall had delicious tomatoes in colours from bright yellow to green to dark purple. Variety is also much better for plants in the long run, because having one type be standard means that the entire crop can be wiped out by a threat affecting that type. And obviously it's much better for the environment if your food doesn't come from halfway across the world. And if you miss having mangoes in winter, then stores like Capers or Whole Foods (in the US) might have ones grown in greenhouses closer by.
- Buy wood from the Forest Stewardship council. Forests are great national treasures and required for our prosperity. Canada is blessed with some of the most beautiful forests in the world, and in great quantity. Thankfully in Canada loggers must replant what they cut down, and we have national parks to preserve the old-growth forests, but not all countries are so eco-conscious. The Forest Stewardship council is an independent, non-profit organization that certifies sustainable loggers, so that you know that no matter where your paper comes from, these gems of nature will continue to exist. The alternative, deforestation, is not only unwholesome but can lead to poverty because wood is required for many societies. Possibly the best example of the difference is illustrated by satellite photos of the Haiti-Dominican Republic border (I'd suggest looking them up right now.)
- Similarly, buy fish from the Marine Stewardship Council. Our stocks of fish are steadily (or rapidly) being depleted, and while it's possible, but not guaranteed, that fish stocks can recover, this slow process is much less efficient than fishing sustainably. Fish farming is an environmental disaster and is no substitute for wild fish. If you'd like your children to be able to eat tuna and salmon, you should make sure the fish you eat now isn't going to prevent that.
- Do NOT drink bottled water! There is no reason that you need a bottle from China, water from a place like Fiji, France, or some tap in America (Dasani and Aquafina are purified tap water) when you can have a reuseable bottle. Most Canadian water is spring water already, and if there's some metallic taste then you can buy a water filter. But please do not get water from around the globe- it doesn't make sense.