For those who saw that @WSJ opinion piece about MD vs PhD Doctors. I offer you this Illustrated Guide to PhDs by @mattmight. PhDs contribute to the body of human knowledge. This is not an insignificant achievement. This title is earned. http://matt.might.net/articles/phd-school-in-pictures/
I also wish to add, this is not a competition. If you have a title or post nominals, whether it is an MD, PhD, OBE, whatever. You have dedicated a portion of your life to a thing. You have contributed. You have achieved. You earned it.
Also, @LiangRhea’s mentor told her women are less likely to use their titles, and encouraged her to use hers. If you don’t /want/ to use your titles, that is fine, but don’t let it be because of patronising BS like that article.