Stay close to work. Patronize the restaurant or deli within walking distance from your workplace.
Eat in. Bring your own lunch. This is a great way to save hundreds or thousands of dollars a year and to do your part to help the planet.
Pack smart. Use reusable, recycled containers and utensils, otherwise Step 2 won't have the dramatic impact that it should. Paying a bit more upfront on good plasticware pays for itself in a short period of time. It is both a cost-effective and green alternative to those disposable plastic sandwich bags that you only use once and have to buy again when the supply runs out.
Bring your own coffee mug. Your leisurely noon coffee can be quite wasteful if you rely on the Styrofoam or plastic cups for your latte or iced coffee. Baristas will be more than happy to refill your mug, and some establishments actually offer discounts to those who bring their own. Just ask.
Forget napkins. Whether you eat in or out, skip the napkins. You may not even realize how wasteful the use of napkins can be, and people rarely use just one or two. Instead opt for an old-fashioned handkerchief, hand sanitizer (no cloth necessary) or other type of reusable cloth.
Choose food wisely. Buy more foods from your local market, and use those for your lunch. Go vegetarian or simply cut back on meat by one to two servings a week. Lunch is an easy way to do this. Pasta dishes are quick, cheap and hearty and don't require meat. Same goes for the old standbys -- with a twist (such as almond butter or soy butter and jelly sandwiches).
Patronize socially responsible establishments. Encourage those businesses that do their part to implement sustainable or eco-friendly initiatives to thrive by giving those restaurants your hard-earned dollars at lunch time.