DH and I still have our first spreadsheet expense trackers from when we were fresh out of college. Our current one has a few tabs:
1. Expenses tracked monthly - each row is a month, each column is a category, with firm numbers for the past and estimates going forward. Every month when we get notice of our bank statement online we open it up and balance everything out.
2. Portfolio tracker - similarly, each row is a month; columns include overall totals, amount entered each month for 401ks and post-tax savings, estimates of future contributions, estimates of future totals based on various market return rates into the future.
3. Retirement expense estimates. This is where we put in our average expenses from tab 1, add in estimates for health insurance, SS assuming it still exists, Big RE Kickoff expenses, taxes, etc. This is where our FI and RE numbers are created. which all feeds into...
4. The Chart - this shows our portfolio totals in the past, with lines for the possible future totals. We can see when the lines intersect our FI number and our RE number. This is the awesome chart that shows the power of compounding interest over years - it's starting to show the parabola, which is very exciting.
Granted, this is almost a labor of love for us, so it's pretty extensive, but once it's up and running it takes maybe 30 minutes a month to maintain. And the psychological impact of The Chart cannot be overstated.