Are you missing succulent green foliage, fragrant flowers, and that humus-y smell of living soil? It may be too cold to garden outside, but it’s a great time to focus on houseplants.
My indoor plants tend to be a bit neglected over the summer. Wintertime is a different matter. I fuss over them, washing the leaves, moving root bound plants into bigger pots, refreshing compacted potting mix, and just generally tidying up. This is the time of year I notice which plants have thrived, which survived, and which really need to go to that great compost pile in the sky.