You can attract and encourage your kids by preparing and packaging their food in interesting way. You can have fun with sandwiches, cut them in different shapes or characters or make rolls of sandwiches as i have shown in my last post. Make faces on fruits like Banana.
Give them bite size food. Protein, fruits and veggie look great on skewer or toothpick and kids mostly like these skewers. Add new food in lunchbox in a small amount and continue to reintroduce it on and off several weeks. If at the end they do not like it then switch it with any other food but from the same food family.
Make the lunch box of your kid more interesting with different ideas. Make a character or right a note on ziplock bag and pack sandwich in it.