Harvard Medical School describes lunchtime at the office as a "minefield of temptation for those trying to eat a healthy and balanced diet." Indeed, if you don't come prepared it's easy to succumb to fast food or vending machines, but even healthy choices, like salads, can quickly turn ‘bad' if you choose the wrong add-ons (like bacon, croutons and high-sugar dressings).

A good rule of thumb to follow for a healthful lunch is this:

• Include lean protein, whole-grain carbs and produce.
• Fill half of your plate with veggies.
• Fill one-quarter of your plate with protein (fish, turkey, chicken, beans, tofu, low-fat dairy).
• Fill one-quarter of your plate with whole grains (a slice of whole-grain bread, a cup of brown rice, whole-wheat pasta or quinoa).
• Healthy fats, such as olive oil, can also be included.

If you're a salad nut, in particular, Harvard recently highlighted the trick to making yours good for you. They recommend avoiding store-bought dressings and mayonnaise-based salads (such as tuna or chicken salad) in favor of the following…

1. Build a vegetable base. This can be leafy greens or grilled vegetables.
2. Add a protein. Garbanzo or kidney beans will add fiber to your salad to keep you feeling satisfied. Other healthy proteins include grilled chicken, chopped hard-boiled eggs or low-fat cottage cheese. When using cheese, choose strong-flavored options like feta or Parmesan, which add a lot of flavor with just a small quantity.

You may be surprised to learn that you only need a small amount of protein, as most Americans actually eat more protein than is necessary. For details, you can find out how much protein you really need here.

1. Add healthy fat. Heart-healthy fats in nuts, seeds, olive oil and avocado add nutrition to your salad while also giving you a feeling of fullness.
2. Get creative with whole grains and fruits. Add some interest and flavor to your salad by sprinkling bulgur wheat on top or adding a few slices of fruit (apples, oranges, grapes, berries etc.).

If you want to add even more function to your salad, consider adding in the following superfoods, which can benefit your mood and more.

• To boost your mood: Add a piece of wild-caught salmon, which is rich in mood-boosting omega-3 fats.
• To bust stress: Add some grass-fed beef, which is rich in B vitamins that are useful during times of stress and fatigue.
• To give you energy: Add a handful of pumpkin seeds, which are rich in energizing nutrients like magnesium, manganese, phosphorus and zinc.
• Extra antioxidants: Add in tomatoes, which are a rich source of lycopene, and raspberries, which contain cancer-fighting ellagic acid.