Ruth and I keep track of every penny we spend. We were doing that even when we had "normal" lives. We found that it was easier to see where frivolous spending was going, and where we could cut back. And doing it daily meant that we could easily see if we were overspending, and when it was time to cut back.
In the old days, it was a simple piece of paper... adding everything up by hand. Then it the late 1990's we got a computer and that made things a little easier. As time went on, I made myself an Excel spreadsheet that keeps annual track of our spending.