Remember when people still counted minutes on the usage of their cellphone service. I do because I still do that. I don't have an unlimited plan, so I am conservative with my usage. And also remember the rollover plan some companies have with unused minutes. What a great idea. It's stuff you paid for, why should you throw it away?
Some times, I like to "roll over" the money I didn't use but was budgeted for. For example, there is $50 budget for small repairs around the house every month. If there is nothing to use it for, it gets added to the $50 for the next month so I have $100 and so forth. So if I need to get a new water heater the next month, I have $100 already for it, so I am only need to add $200-300 more instead of $400. I don't keep it in a separate account. There would be too many accounts to keep track of, if I had one for every category. But it would be nice to look at!
Not sure if anyone else do that or I am doing silly mind trick with myself. If I rolled over my personal spending amount every month, it would give me more motivation to "save" for something that I want to splurge on. Let's say I have a budget of $50 spending per month. Every month, I just have to stay under budget. After 6 months, I could potential have $100 unused money rolled over in my personal spending. Then I could splurge one something that is the amount in my rollover, in this case it's $100. I wouldn't have to justify to myself that I am splurging once or feel guilty that it comes out of any other pile of money. It's money I already "spent" or budgeted for but not used. Or think of it as prepaid installments instead of credit card balance minimums after.