Use a reusable bag. Go vegan. Bike to work. Get a job at a nonprofit ...

There are many things all of can do to make our lifestyles less damaging to the planet. And yet few, if any of us, are doing everything we can. In a society that incentivizes consumerism, waste and fossil fuel use, even relatively small lifestyle changes can feel like you're swimming upstream. So how to prioritize?

Here are a few suggestions:

Weigh the impact

For the longest time, the green movement seemed obsessed with small, easy lifestyle changes, promoting the notion that turning off the lights or grabbing a reusable bag might eventually turn out to be a gateway drug to more impactful actions. But in a world of escalating climate change impacts and runaway extinction rates, this every-little-bit-helps approach is starting to feel a bit naive. Instead of beating yourself up because you keep forgetting your tote bags, why not pick one or two "big" things that can have a significant impact on your overall carbon footprint? And then cut yourself some slack on your smaller transgressions.

But what are those "big" things?

According to Inhabitat, going vegan could save 1.5 tons of CO2 emissions a year and switching your gas car to a hybrid could save a ton. And if you're in a state where it's allowed, the single biggest thing you can do is switch to a power company that sources from 100 percent renewable energy. (After all, the power sector is the single biggest contributor of carbon dioxide emissions in the country, according to the Union of Concerned Scientists.)

You don't have to commit to all of these big-ticket items, but pick something ambitious and go for it.

Make it sustainable, in more ways than one

As anyone who has broken a New Year's resolution knows, a lifestyle change only has an impact if it's long-term. So alongside weighing the impact of your new commitment, think about how realistic it is for you to commit to it. Love bacon, or live with a butcher? You might do better to commit to reducing your meat intake rather than going cold turkey (sorry!) overnight. Similarly, if you commute long distances or have family who live out of town, you will do better switching your car to something less gas guzzling rather than going car-free.

The flip side of this principle is to focus on the things that get you excited — because those are the things that you're most likely to stick with. For me, for example, I get a huge, geeky kick out of composting — so we now have four different composting systems running simultaneously. Just find the things that will work for you, and start there.

Don't forget the day job

We can do many wonderful things in our spare time, yet we spend a large chunk of our waking hours at work. So finding ways to make our work life a little greener is probably one of the single biggest things we can do to promote sustainability. That doesn't mean you have to quit your job at the oil company and go work in solar — although you certainly could. In almost any industry, there are opportunities to promote energy efficiency, recycling, waste reduction and renewables. And if you really do want to make a shift to a greener career, check out the growing number of mission-driven B Corporations that might be looking for talented new employees.

Money makes a difference

It's easy for most of us to understand how our electricity use leads to pollution. But what about retirement savings, or the nest egg in the bank account? Whether it's divesting from fossil fuels, investing in renewables or getting involved with shareholder activism, there are many ways to make your money work for you and the planet and earn a decent return too. This article by Michael Chamberlain for Forbes breaks down socially responsible investing. It's also nice to know that once you've put your money somewhere where you know it will do good, you'll be having a positive impact without even having to think about it.

Seek systemic change

Perhaps the biggest thing you can do is to remember that none of us can do it alone. For the last 20 years, the environmental movement has pushed personal lifestyle change and incremental steps as the best way to change our culture. But that is shifting. With the growing realization that our environmental crisis has systemic roots, there's a shift in focus from our personal behaviors to our collective impact. Whether it's voting for a candidate who will cut fossil fuel subsidies, or campaigning for a change in corporate behavior, the biggest single thing that any of us can do is make our voice heard and start to change the rules of the game. Once we start creating an economy and a culture where sustainability is incentivized and the polluter pays, then doing the "right" thing will become second nature to all of us, without having to think about it.

Which lifestyle changes really make a dent in your environmental impact?
In a world where almost everything we do has an impact, it's hard to know where to even start.