Healthy happy meals are the ones we make for our children ourselves. I was answeing a blog a young lady posted and it reminded me when my girls were young I would take them hiking and put their sack lunches in their backpacks. Keep it simple and heat resistant. Peanit butter and raisin sandwich on rye or wheat bread, dried fruit, carrot sticks, uncooked green beans (washed and blached if preffered) juice or milk in non refrigerated carton (I would fill a water bottle and disperse the juice during meals) slightly frozen, They can spend the previous day decorating the bags themselves by drawing, painting, collaging, stickers, etc.
a bonus was each had a prize in their bag. When I went to wal-mart, I would buy a small bag of party favors or use the machines where you stick the quarter in the slot and turn the knob.
Remmember to keep little ones hydrated, stop every 15-20 minutes and have them drink water, also I never made them finish if they felt full. It can be saved for later, but children's appetites are different because they have different metabolisms. I'm not referring to family meals but I would not stuff one of them and expect them to climb down a tall hill.