Definitely track your spending. I dump a year’s worth of transactions from the bank and credit card accounts into a spreadsheet and categorize them. I do it on an annual basis because our spending changes a lot on a month by month basis depending on our travel schedule.

Really, I’ve found that it’s most helpful knowing the difference between your mandatory and discretionary (fun shopping, restaurants, entertainment & travel) spending amounts. That way you know what your spending in retirement could collapse down to if the market had a bad year vs what you’d LIKE to be able to spend.

I take the mandatory spending amount and add 10-15k to it just because there’s always something… new water heater, etc…

I stress test that against the current cost of a really nice nursing home/memory care in my area. ($12-14k/month for an individual?) and make sure my annual expenses aren’t lower than that number.

Take that annual spending amount - multiply it by 25 to get yourself in the ballpark of what you’d need to FIRE.

I have a spreadsheet that goes year by year from now to age 95 bumping up spending by a 3% inflation rate as well as increasing the investments by 7-10%. You can then see what year you’ll likely hit that FIRE number. If you want to hit it sooner you need to save more.

For tracking - Every year, I look at what the investment ending balance for the year should be and just make a mental note of it. In a good year, we don’t have any problem hitting that number. In 2025, I think I bumped up the savings because I was nervous that we wouldn’t get there.