Cut chicken breast
1/2 sweet potato
You can weigh out your food if you want, but I do enough math at work. Eyeballing it is just fine. Your body has no clue that you ate 0.5oz over of protein. Just keep your portions modest. You're not trying to stuff yourself. The important thing is getting the multiple meals in. If you're lunch break is at 12:00pm, try having 2 preps at 10:00am and 2:00pm, so you'll eat two times while at work.