This visualisation technique can be used for small and big decisions alike. Thinking of eating that extra piece of cake? Walk yourself through the likely thoughts of your future self. Want to spend a large sum of money on a piece of tech you’re not sure yet how you will use? Think about how your future self will feel about the decision
Note that these are examples that imply that using regret of future self in decision making is mostly for deciding against a certain action (eat cake, buy new toy).