I ask this question, not as someone who has REd, but as someone who's company is going through a big re-org and who has enough to scrape into RE. (41, pension drawdown from 57, enough after tax savings to bridge the gap with the smallest of margins)
I've found the things that motivate me, and bring me joy, are those which I think are important. They may be small on the overall scale, but I can leap out of bed in the morning because were on the verge of breakthrough in a big project at work, or because I think I can make things better at work by fixing something. The things which bore me to tears are those where I feel like I'm not adding any value, things which are pointless. Supplier reviews, budget planning, HR policies.
I've been thinking what my future might be, and Mrs NM has quite rightly pointed out that I'll go very quickly insane if I don't have any of the things that i need to fix to go and fix.
For those FIREd, how did you find the thing that it was that you needed to do? r