...... For me running or walking is a great way to escape the in laws rather than to keep fit. Literally running away from them as they start to bicker is a wonderful feeling.....
Now that you've identified yourself, I take it they won't be reading this. 
It's difficult to ignore Christmas completely but we try our best I think it was a couple of years ago that we did a wild camp on Xmas Day, it was very satisfying. Felt like quite an achievement to escape and do our own thing
.....but I did have to live with the guilt
Whilst keeping up the 'bah humbuggy' approach, this year requires more of a balancing act. (And we do actually have some nice rellies that we'd like to catch up with.)
So mostly dashing around seeing folk on Xmas and Boxing day, then it's off to the hills unless the weather is really p!sh.