I think the key is to keep working in FIRE as hard as before, but on goals, things that fulfill you, and make you a more balanced person, on your terms. The appeal of FIRE shouldn't be inaction, but rather purposeful action, i.e. you work hard all day on something, and instead of thinking "well, good for my boss I guess", you reap the rewards yourself. It allows you to work on YOUR goals and achieve better balance, i.e. if you find you need more human interaction, you can work hard towards that instead of slaving away at the computer for 8+ hours like your job requires you to. Jobs with balance are rare; that's the price we pay for division of labor and luxurious lifestyles, we become unfulfilled robots.