<prompt> Human: I kept checking my account to see if I had money. I did. By Monday, I was negative 50. I thought getting a daily account balance reminder would help but it did not. I think some places I went shopping at did not charge me until Monday over the weekend. How do other people handle this? Should I only carry cash on weekends since it seems that the balance reminder emails are not accurate?  <response>: A generation ago, people would only get balance notifications from their bank once per month, in the mail. As a result, each person would keep his own handwritten record of his current balance, would carry it around with him, and would update it each time he made a purchase or a deposit. Once a month, he would compare it with the banks notification to ensure correctness.Fortunately, we have smartphones now and you can do the same thing using your smartphone. There are plenty of apps for this. I use YNAB, but there are many others. 