Here is the useful list for reading about comfort zone:
http://blog.pickcrew.com/getting-out-of-your-comfort-zone-why-its-hard-and-why-you-should/
Here is the specified list for measuring personal comfort zone and you will get more help and tips:
http://www.whatismycomfortzone.com/
Getting out of your comfort zone.
原文：http://www.cnblogs.com/freecodeX/p/4236710.html