It's not whether you as a single person can make a difference in the world. The question is really about how large your impact is based on decisions you make every day. Everything you choose to eat, where you live, what you do throughout the day, how you get there, what you buy and where you shop, are all ways that you have an enormous impact on the planet. For many, it may seem overwhelming to worry about so many decisions, and so they form this opinion that they can't make a difference or they simply develop complete apathy towards the environment because it's far easier on their conscience. The truth is though that as someone who is living in a developed country, every single decision you make is an important one. The real question is how do you go about making the right decisions every step of the way? How can you make it easier on your decision-making process by instituting small steps? For example, the fact remains that even simple steps like not using styrofoam and bringing containers to the restaurant are easy. They may be inconvenient the first time; however, once you get in the habit of bringing them with you to the restuarant, it becomes second nature. Similarly, having reuseable grocery bags with you when you go to the store is a no-brainer. And instead of cutting out meat entirely, swtich to poultry, or gradually reduce your meat intake by having vegetarian recipes that you keep introducing into your diet. Maybe you realize that instead of sitting in traffic for 2 hours each way to work, you can take light rail for part of the way and ride your bike the rest of the way.
Today though, I suggest one of the biggest impacts people have on the planet is through consumption. "Consumption contribut[es] to more than 60% of global greenhouse gas emissions and between 50% and 80% of total land, material, and water use." Unfortunately, the vast majority of this consumption ends of up in a landfill (GIFT OF DEATH). Luckily, there is no shortage of ways for you to minimize your consumption. Here are several resources:
1) GREEN PEACE - 10 simple ways to use less oil
2) The Lazy Person's Guide to Saving the World - 17 Goals to transform our world
3) Eco-friendly Apps - Apps to Help You Help the Environment
These are just a few suggestions. Please feel free to contribute other ideas to help us reduce our consumption.
And here's a link to a great piece about our fascination with consumption: