Budgets

Why is it so hard to keep a budget? I don't understand...We eat chicken, tacos and spaghetti and yet spend so much money on food. We constantly go over budget on food and supplies.
Maybe we should quit eating?
We drive used cars that are paid for.
We bought a foreclosed home at a GREAT price.
We haven't gone on a vacation since our honeymoon.
???
It also doesn't quite seem to make sense to me that our income has gone up significantly in the last 6 months and we no longer have a car payment...so where they heck is all of that extra money going?
If anyone knows please call me...
It is so frustrating.
I guess it must be obvious but so far, I haven't been able to figure it out.
Help?...