Writing Christmas cards ranks pretty high on many people's lists of tedious festive chores. That's if you actually send any. However, there are a couple of ways you can make it easier.
The first option is to design a postcard-style card online that has a stock phrase, which you can post to everyone without having to hand write anything other than their address.
The second option is to buy cards small enough to fit in your bag, and write a few whenever you have an idle moment — on public transport, waiting in a queue, etc.