I retired in 2020. Went back to work part-time not because I needed the money, but because I think it helps maintain mental sharpness.
I've read a lot on how to maintain one's health and mental acuity as one ages, and a few things stick out. One is challenge oneself mentally with new hobbies, whatever. Doing the same-old, same-old doesn't cut it--you have to build new pathways in the brain.
The second element is being physically active. There are lots of ways. Some people walk a lot. I work out 2-3x per week, half-hour of cardio, some upper-body lifting. Otherwise you'll devolve to the level of activity you engage in.
The third is social. That can take on a variety of forms. I am on a couple of volunteer committees, heading one of them. I also play poker, golf, and a few other things that get me out of the house and interacting with others.
I'm still working part-time because my former job asked me to come back PT, and they made me an offer I couldn't refuse. It forced me to get my head back in the game, and keep it there. The income I derive goes to support my various hobbies. I brew beer, fly, play cards, shoot trap, reload....all those are part of keeping my head active.
Works for me, but I think most people can benefit from the mental challenge/physical activity/social elements in their lives.
PS: My job isn't at WalMart.