Stay hydrated - don't forget water as well as tea and coffee. Central heating can be very dehydrating. Warm water with a slice of lemon or ginger can be very refreshing. And being well hydrated helps with your energy levels, digestion and ability to get rid of toxins (just in case you have the odd festive night out!).
Get outside in daylight - this will help you body and mind know which end is up despite dark morning and the evenings drawing in. It helps both your mood as well as your sleep patterns.
Get a variety of fruit and veg into your diet - salad season may have passed but having plenty of good quality veg will help keep your gut healthy and give you the nutrients you need to support your immune system. Use spices to give them some heat and and generate your own central heating!
Keep moving - don't hibernate completely, find some places to walk where you can find leaves to kick or crunch in. Or join a cosy new yoga or pilates class. Or, of course, come and join me in any one of my 5 classes a week to get some fun, fresh air fitness.

These are simple things. But they can make a big difference. See if you can get your 5 a day this winter.