Author Sam Beckbessinger's excellent book Manage Your Money Like a F*cking Grownup is the unofficial written summary of The Fat Wallet Show. While we didn't know about Sam nor she about us until after the book was published, we are thrilled at the synchronicity.

She explains every principle you'll ever need to understand to make excellent financial choices simply and understandably, sometimes even with pictures. In fact, if you never read another thing about your money, you'll be set for life.

We couldn't imagine a better co-host for our 100th celebration. We spoke about the one concept in her book that we've never dealt with on this podcast (because I didn't know about it) - the spending ratio. As Sam explains in this episode, it's an excellent way to measure the health of your finances, because it's not dependent on external circumstances like the market or even your salary. You are in complete control.

To work out your spending ratio, divide how much money you put towards paying off debt or savings of any kind (including retirement and emergency fund) by your after-tax income for the month. Times that by 100 and you have the percentage of your income that you spend. Your challenge, should you choose to accept it, is to reduce that number as much as you can. The lower your spending ratio, the higher percentage of your income actually serves you.

Sam's book also deals with the most common behavioural traps we fall into when it comes to our money. I caught myself making the most obvious one as I was reading Sam's book - mental accounting. I caught myself before I made the mistake and saved R600! Not bad! In our conversation, she explains what mental accounting is, why we do it and how we can try to get around it.

Lastly, we talk about the final frontier in my budgeting quest. I've become very mindful about my money and deliberate in my savings over the past five years, but I've always struggled with discretionary spending. I allocate funds to certain spending categories, like groceries and petrol, but never seem to stick to that. Sam's book finally solved that irritating problem. She explains why it can hurt being too granular in your budget.