As I am nearer to this point than I'm happy to admit (and I have absolutely no retirement funds in any way), I would first ensure a comfortable retirement for the rest of my life - commencing immediately.
I would buy a nice condo; I am not interested in yard work or outside maintenance and since I'm on my own, a lot of space isn't a requirement. But I'd rather have the tax benefit of owning rather than throwing money away renting, which I'm doing now. I'd also buy a nice car Tesla or Audi. All this at cash; I refuse to have "payments" any more!
I'd have a personal trainer/nutritionist keep after me so that I work out and take care of myself properly. I would pay off my debts (currently below $5k, so that's not bad) and ensure my son was set up well enough so that while he would still need to work -- young men need to work -- he wouldn't have to worry during downtimes and he'd have the flexibility to do what he wanted in life. I'd make sure my parents and siblings were set up properly, as well. One brother has a large family (with two in college and another off in about two years) and I wish I could help him more. I would donate a significant portion to personal charities.
My job is okay but it's always just been one to have money and benefits; it's not a "love" and I wouldn't mind not doing it anymore. Instead, I'd fill my time with travel as often as possible (and be able to afford the stinking SINGLE SUPPLEMENT!!!
). There are so many places on this Earth that I've wanted to see and I'd love to be able to have a holiday that didn't involve sweating every penny and knowing I'd have to get back to work more tired than when I left. Along with that would be an indulgence in my hobby of photography.
I would indulge my love of the arts. I'd go wherever I wanted to see whatever concert, festival, theatre performance, opera, etc. appealed to me. I'd have an excellent home theatre set up. I'd support local artists by purchasing and contributing so they could continue their work. I think I'd also buy a horse. I've always loved to ride and have never been able to as much as I'd like (it's an expensive hobby). I'd board him at a local stable and enjoy that hobby like a mad man! More fun than a dog.
I can barely imagine the lightening of stress not living paycheck to paycheck. It's a fine fantasy.