Currently I'm shopping around for a new gym, but I walk when I can and if the weather is bad I try to spend a little time on my treadmill. My daughter and son-in-law have picked me up several little practice gizmos to mess around with, so I can always have some fun with that in the meantime to practice a bit as well.

Going to the gym (Goodlife Fitness) 5 times per week working on strength and flexibility. Like you, recently retired and looking to find a focus in the winter now that the colder weather is upon us. Lots of putting practice in the basement.

With golf season over, a more sedentary life sets in. I've gained 6 pounds, 4 of which came during the week of deer camp. Too much heavy food and drink. Time to get into the winter program. My gym workouts start and end with cardio. Weight lifting for strength, but not a lot of heavy weight as I don't need to build bulk and lose flexibility. A lot of core exercises and stretching. When I don't get to the gym, like weekends, stretching and planks is at least something needs to be done. If I don't it doesn't take long to feel the adverse effects. My Dad used to say "It's hell getting old". At 60 I'm beginning to see what he meant.

I do crossfit 4 times a week, and romwod for flexiblity and stretching everyday. Over the last 2 years i have really focused on my nutrition and fitness and it has made a world of difference in my golf game. I have more energy and do not get tired toward end of round, i have gained 10
carry yds across board from irons to driver. my handicap has come down from 6.5 to 1.9 over these last two years.

Indoor rowing....it is great for the core, back, and legs. Stretching to mimic golf swings, walking (especially stairs) whenever possible. My lovely wife invites me to to yoga class on Saturdays, but I struggle to relate "downward dog" to anything that I do on the golf course.

I saw something about 18strong.com

I haven't tried it, but maybe you will have luck with it.

Over the winter months, especially living in a cold climate, I try to keep the weight off and maintain my flexibility. Lots of chipping and putting around the house, lol.
I'll play as long as the courses are open! But like the OP said, mainly trying to keep from becoming too sedentary over this time.

Every morning ( except Sunday) Floor exercises taken from the Titleist Performance Institute and Dr. Rose for about half an hour. After the floor exercises half an hour on the Tread climber. Three times a week resistance exercises off days some Yoga to maintain flexibility. All this to try and keep the weight off.

For me in the winter months I just continue keep playing golf.
No weather condition is too hard for me. I am a real die hard out there!

I live in San Diego so there isn't a winter but I did pick up Joey D's book called "Fix your body, Fix your swing" and I am working on my hips.

Rob,
Where did you find that book looks interesting..

I run and spin 5 days a week. I have horrible flexibility so I’ve just started yoga hoping that helps. Feels a bit foolish at first but it’s pretty tough so I’ve stayed focused on that. I also signed up for a simulator membership for the winter at our course on base. Nothing like playing g a round at pinehurst on your lunch

If it's nice and cool outside i enjoy running around a local lake trail, if I have time to spare on the weekend I try to go run a couple miles, other than that I keep up my regular gym routine lifting weights 2-3 days per week, and I also ride a stationary bike at the gym when I'm there. After the new year I will probably have to limit my gym to just on the weekend afternoons, all the new year resolution people make it impossible to get a good workout in during the week.

Ice hockey.

3 rounds of golf and 3 days of practice a week.

I go to the gym 4-5 days a week, I started taking group classes now 3 of those days & it's light workouts with cardio & core built in. Not looking to pump up just maintain a good healthy body & energy level for the warmer months of golfing & playing with grandchildren,

DM

Coffee EVERY morning...rain or shine. Cheeseburgers and pizzas semi regularly.

Tiger Woods golf on Xbox haha! But seriously midwest golf is tough in the winter!

I continue my normal routine on my off days. I work in a firehouse that has a gym so I'm pretty lucky.