For many of us busy people, breakfast can often become a thing in the past, something we leave out during a hectic morning. Then, in the middle of a busy morning at work, we begin to hit a little speed bump – we feel a bit tired, or our stomach starts really growling, and our eyes look to the clock, wondering when lunch is. By the time lunch arrives, we’re ravenous.

That was me, at least, until I realized that I needed to start eating breakfast. I was worried that it would cost me money, because I’d have to start buying food to eat in the morning. But the surprising part was when I looked at my finances a month after starting on breakfast: I had saved quite a bit of money!

Here’s why. Without breakfast, by the time lunch rolled around, I was very hungry and not thinking rationally about food. I’d go out with co-workers or eat somewhere expensive by myself. After I started eating breakfast each morning, I was much more level-headed come lunchtime and able to make more sensible dining choices. Right there, I began to save an average of $3 a weekday on lunch.

But it was still expensive; I often stopped on my way into work for something to eat, and that was costing me more than the $3 each day I spent on lunch. That’s when the “second rule of breakfast” became clear: eat something small at home before you go. I began to eat a container of yogurt every day before leaving for work, which cost $0.40, and this had the same effect of reducing my hunger at lunch. Overall, I was saving about $2.50 a day.

Of course, this still meant that I was spending too much money eating out each day, but that’s another problem to solve.