In that attempt to stay fit, have you considered rowing?- indoors on a rowing machine- that way you can do it all year round whatever the weather. There is also an advantage in that it exercises the legs, arms, chest and back all at the same time. Furthermore it can be done at your pace or against others.
Can I suggest that you look at Concept 2 indoor rowing machines?
Here are a few pictures of the rowing machine and the various programmes you can select. I have for some time been choosing a standard list row of a fixed distance- the beauty of that is that I can compare one days row with another.
There is also an online log book run by Concept 2. If you are feeling keen (or competitive) you can look at what times others have logged overall or just in your age group. I suggest that you restrict it to your own age group as there are some ultra fit rowers out there. They are also from around the world.
The technique of rowing takes a little time to master to a high standard and in searching the net I found the following from the Telegraph from July 2017.
There is also a useful piece from Concept 2 at https://www.concept2.com/indoor-rowers/training/technique-videos
A third and final suggestion is from Coach magazine. I will mention them again in the future. It an online magazine which has regular suggestions of what else to do keep fit. And getting stuck and bored with a fitness regime is the easy way to go nowhere.
Incidentally with a Concept 2 rowing machine you can avoid that old statement ” it was a long walk/swim home when I discovered how unfit I was”
One of the gyms I visit is near a classic large river well known for its rowing. Perhaps that was why they had a comprehensive collections of Concept 2 rowing machines- 8 of them side by side.
Just not sure where the cox is supposed to sit or if you fancy it you can pay a PT to shout instructions at you, a faux cox if you like
Finally the Concept 2 log book can keep a running total of how many Kilometers you have done in a lifetime. I’ve been rowing off and on for some time (it would be indiscreet to mention how many years). I did recently reach one of those mini milestones.
And by sheer chance when I did there was a rainbow outside the gym.
Still not reached the pot of gold but it was encouraging all the same.
Will just have to keep going. Enjoy your rowing/fitness/retirement.