Well, we shopped around for the cheapest satellite deal (dumped cable which was way too expensive - but can't go with just an antenna because my husband has certain *standards* that he can't live without) and we went to a slower internet connection. The food budget got cut way back because we switched to a discount store - that was my thing, I had to get used to generic stuff because I was a brand name snob, but once we made the switch we literally cut our food budget in half.
We changed car insurances and saved a ton of money (no, it wasn't GEICO)
, set the heat on a slightly lower setting, even changed life insurance companies to cut our premiums in half (but still had better coverage - being a teacher has some perks).
So my main advice is to look at each and every bill and see how you can cut it. Even saving $5 or $10 a month on a bill will add up over time. It gets to be kind of like a game, seeing where the best deal is. It makes me wonder why I was so content to waste money on things before.
I'm glad you can make it! Paying the mortgage is a huge stressor but now you know you have the money (I love Excel spreadsheets, too - I have about a dozen going all the time with different calculations and stuff for both the budget and my weight loss).
Hope you're feeling some relief from the stress now that your budget is set out on paper.