Computer games. Catching up on processing a huge backlog of images. Read some - not photography - books. Experiment with diffusers etc. Find little things out of doors even though most of the insects etc have disappeared - little animals (I think perhaps springtails are around in the winter for example. I think I recall seeing photos of springtails in icy conditions), and plants too - there can be some interesting colours and textures to work with. Moss and lichen too perhaps. Water droplets on grass etc. Ice. Use the camera to look closer than usual at various things and pictures can appear out of nowhere.