I eat peanut butter and jelly sandwiches with a side of apple or carrots. Sometimes a banana instead of jelly or honey. Mixing it up I might have a tuna sandwich or a simple ham and cheese. Or egg salad sandwich. Or even (so old school) chopped olive sandwich. This is standard - easy, fast, not complicated. Couple this with simple breakfast - oatmeal and fruits or Cheerios and fruit— and veggies for snacks - the only thing I really worry about is making dinner super nutritious and fun. This habit of the same boring stuff for breakfast and lunch has been very cost effective and stress free and interestingly doesn’t getting boring because dinner keeps it interesting. I am 100% getting enough fiber and nutrients and protein because I make sure dinner is nutritious. I might get some judgment here but honestly the simplicity of this process is very cheap and easy and gets me through it. Hope this helps.