Go to your local library to check out what's going on for people of a certain age in your area. Most places have a U3A (University of the Third Age) and for a small sum payable annually, there are varied things to do that might interest you, from learning a language, to visiting local attractions with historic or cultural interests, to playing green bowls. Look online to see the details.
Many adult education centres have 'summer school' where for 6 weeks you can learn how to do something. I did a quilting one once where I learned how to do patch work. Again, once holidays abroad open up, it's always good for our image (us Brits are notoriously lazy at learning even a few words of our host's language - please, thank you, hello, etc) so do a basic language course. It's usually free or subsidised (depending on your council's generosity) and within a few months, you could be talking like a native. The important thing is not to stagnate.
Good luck.