people do.

Do a spreadsheet of all your expenses and your income. Every category. I have done this for every year till I am 90.

I have separate inflation percentages for each category of expense. And I can easily adjust income and expenses up and down to test sensitivities.

Don't assume you will get 8-10% return on your investments. I assume 6 or 7%. I think that is more realistic.

Basically you can do a much better job of predicting your financial future than any web site model can because you should be able to add all sorts of details that no model can do for you. This takes some time. As in dozens of hours. You have to understand the rules for withdrawing from 401K/IRA and how medical insurance works as a retiree. If you are not an excel whiz kid, then learn all the basic stuff. There are lots of issues to look into. But I am so familiar with my financial situation, that it makes it easy for me to make decisions and I know exactly how it will impact our future.

This isn't to say you have to stress about every dollar spent and saved. In reality I have less stress because I am not guessing about what the future may hold. You can't control everything, but being as educated as you can be about the stuff you can control is pretty good advice IMO. Then you won't have to come and ask a bunch of strangers what your retirement strategy should be. Or at least you will have a really good background when you do.