Step 7 to 8 people: how to you decide what to spend and what to save?

For those of us lucky enough to be at step 7 to 8... how do you decide on how much to put into 5 year spending goals and how much to put into savings/investments/mortgage overpayment?

I guess this is more of a psychological question, and the exact split will be different for us all. But how do you personally decide? Do you have a logical system or just go on vibes?

I got so used to saving as much as I could to buy a house, that I now find it hard to judge whether something is frivolous/impulsive vs something that is worth spending on!