Dear friends:

Now the outside was covered by the snow. A pure white world, peaceful and beautiful.

I personally prefer to stay inside the warm warm room and not stepping out, I am even lazy to move around, which means don't have "enough" exercise, no enough  stretch enough is not good. And coming inside and outside of the room with big temperature difference is not that good for knees.

My dad has problems with his knees: rheumatoid arthritis. In Chinese, the sympthom is called "wind-damp". And it seems that everytime he experienced temperature difference, he feel uncomfortable with his knee. This is kind of chronic disease which gradually burst out. So I am just thinking we need to pay attention to protect ourselves when we are young.

Do not stay somewhere for a long time, just stand up, move aournd, and stretch out. Also, enjoy outdoor sports is a good choice. Get some fresh air, why not?