Best financial advice you've ever received

Have you ever received an advice that change your life? Mine is " You can't spend the money that is not in your disposal” My uncle told me this in 2019 when I was spending all my salaries and by the 12th, I had already spent everything and wondering where it went. Now, any time I received my salary, I move 30% to a savings account. I only spent what I have at my disposal.