This suggestion from nutritionist Milk & Honey Nutrition is brilliant. I work from home and often use this method to build balanced lunches while I work.

Pick one item from each category:

1 or more proteins2 oz turkey or salmon
3 oz tuna salad
2 deviled egg halves
1 cup Greek yogurt
3/4 cup cottage cheese
1/2 cup roasted chickpeas
1 carb or grain serving1 oz whole-grain crackers
1 oz pretzels
1 slice whole-wheat bread
1 small muffin
2 small corn tortillas
3 oz cooked sweet potato
3 cups popcorn
1 to 2 healthy fats1/4 avocado
2 Tbsp nut butter
2 Tbsp shredded coconut
1 oz cheese
10 olives
at least 1 fruit1 cup berries
1 small fruit (4 oz): apple, orange, pear
2 small tangerines
1/2 cup grapes
2 Tbsp dried fruit or raisins
12 cherries
at least 1 veggie or side salad1 to 2 cups dark leafy greens: spinach, kale
1/2 cup cooked veggies (non-starchy)
1/2 to 1 cup raw veggies: cherry tomatoes, cucumbers, red bell pepper, snap peas, snow peas
1 oz diphummus or guacamole
salad dressing
pesto
yogurt dip (mix 1/4 cup Greek yogurt + 1 Tbsp apple cider vinegar + 1 tsp mustard)
something funpickles
nuts: 15 almonds or 1/4 cup trail mix
1 oz dark chocolate
1 small cookie
Pick one from each category

Example meals:

1 to 2 proteins

1 veggie and 1oz dip

1 to 2 fruits

1 oz healthy fat

Something fun

2 deviled egg halves

Snow peas and tsatziki

Apple slices / grapes

Peanut butter

1 oz baby pretzels

2 oz turkey

Cucumber salad

Strawberries / yogurt

Mozzarella balls

15 almonds

2 oz smoked salmon

Baby carrots / hummus

Blackberries

Cheddar cheese

Wheat crackers

2 oz chicken

Red bell pepper / yogurt dip

Tangerine

Avocado

1 cookie

2 oz tuna salad

Cherry tomatoes

Pear

Babybel cheese

Rice cakes