"My favorite healthy, packable lunch is a grilled chicken breast with 1-2 tablespoons of honey mustard," said Staci Gulbin, MS, MEd, RD. To fill out the lunch, she slices up an apple and adds a tablespoon of peanut butter for dipping. "This lunch is simple and easy to prep the night before," Staci explained. "The chicken can be leftovers from your dinner meal and tastes great warmed or cold." It's also rich in protein and fiber to keep you full until dinner.