I'll add it is important to just "attempt" to be FI, and can pay off well before you actually are. This is what I like to point out to all the FIRE haters that talk about how the many years of saving is nothing but sacrifice, a sacrifice that lasts a significant part of your life and so may not be worth it.
I hated my job, both the job and the way it took me away from my family for hours and even days upon days, but it paid well... I looked up one day and had savings equal to 5x my annual spend and wondered, why in the hell am I here. Why I dont I leave, find another good job, not accepting just a stopgap, and consider the time looking a vacation as opposed to being unemployed. Most people my age at that time don't have months, much less years, of savings that made this a reasonable action. And the only reason I had all that savings was because a few years prior I had become determined to FIRE.
When I hit about 8x savings (well before the FIRE goal), it occured to me that I had no financial worries beyond one "exactly how young can I retire?". Not what if I lose (or leave) my job, what if the car breaks down, what if my insurance doesn't cover everything. That's an awfully comfortable place to be.
Many years later, now FI, it turns out I think it is good for me to have a part time job (worked from home) for a few reasons (similar to how it is 'good for me' to exercise, even though I don't always love it). But it has to be ridiculously perfect, which is what I held out for, because I could. And I got it. And I could lose it tomorrow, and that is ok too.