Easiest Step to Being Green Ever?

Here's an interesting thought experiment: what is the easiest step an individual can take to become more eco-efficient? Some simple steps can have large benefits. For example, environmentalist David Suzuki says some simple ones are: "Making small energy-efficient changes to your home" or "Not buying pesticides or herbicides". Others take an activist approach and say "Writing one letter to a retailer, and request they stock eco-friendly products". Others theorize we should start with food, offering these steps: "Growing some of your own food" or "Buying local or organic food where possible". A more long-term step, but certainly easy is: "Making the next car you buy more fuel efficient".