With two young kids
we used to, still do to a certain extent but it’s changed a bit, do indoor things. Embrace being inside your house that you work and pay for.
We would have Saturday afternoons when we made a warm dessert (sticky toffee pudding say) - it was time to teach the kids to cook (obviously not anything nutritional to begin with) but warm puddings they could get behind.
We would play, I would get them to vacuum, lots of radio music was played, we would still go out and a run around the park blew the cobwebs away.
We would get morning jobs in the house done, saves doing them when the warmer weather turns up.
I like January, it feels bare, clean, fresh after the excess of Christmas.
I buy Seville oranges and make marmalade (that is their one season Jan/Feb) takes a while but finely slicing orange peel makes the house smell fresh.
You can forget the joy of reading, January is a time for dystopian fiction and pencil drawing.
Basically a time to cleanse the body with simple food, feed the mind instead of the body with reading and ticking off jobs, and enjoying your home with all the toys, puzzles, games and tv that you enjoy.
Think of it as the blueprint month for the rest of the year.