Been following this thread and hesitated to post, but I seem to be the outlier.
I retired June 2016 and stayed 100% retired until March 2017, at which time I took a part time job at the elementary school up the street (100 yards) as a dishwasher. I'm still there 25 months later.
It's not a bad gig - it's only 3 hours a day, I get a free lunch, and I don't have to be in until 10:30. More importantly, I don't have to work nights/weekends/holidays and I have the whole summer off. No commute and the school's closed whenever there's any snow.
It pays about $15 an hour BTW. It's not hard work (compared to a fast food restaurant) but it gets busy at times so sometimes you have to hustle.
Why did I do this?? I definitely wasn't bored in retirement.
A couple of reasons -
1. I was uncomfortable with the new regime in Washington DC (he who shall not be named). Was the sky going to fall in?
2. The state of ACA (attempts to weaken/repeal it). I do have the option of healthcare with my former employer, but it's non-subsided so it's pricey.
3. Short term market volatility made me question things, like my withdrawal rate (should I stick with 4%, 3.5%, 3%, etc.)
4. Having a paycheck again made me feel better. I started playing mental games with myself - hey I made enough money this week to pay for the landscaping stones from Lowes, and I earned enough this year to pay for most of the planned re-roof job coming soon.
5. If I had earned income, I could contribute to my Roth IRA, which is never a bad thing.
6. I swore to myself I'd never get another job in IT after 33 years. Despite the good pay, I'm done with the deadlines/commute/stress/competition/learning curves of new technologies.
Fast forward 2 years, the sky hasn't fallen in. The ACA is still alive, and we have more $ in our retirement accounts than when I retired in 2016 (by about 20%).
Sometimes I do question my own sanity - I do wonder how many multi-millionaires would work as a dishwasher (probably not many).
The bad thing is that 2 years have gone by, so I've lost 1,140 hours of quality retirement time I'll never get back.
Be gentle, like I said I do question my own sanity.