"In the event of an emergency, a mask will drop from the ceiling in front of you. If you are traveling with a child (or a person acting like a child) please place the mask over your own nose and mouth first and breathe deeply. Then give aid to your companion."
They tell you that explicitly because they know that your first reaction as a mother will be to help your child but the message here is: Take care of yourself first or you'll be no good to anyone who might need you.
The answer is always available you just have to ask the right question. Help is always there you just have to know where to look for it. Sometimes its right in front of you, dropping into your lap in the event of a crisis. You just have to be willing to take it, use it and BREATHE. Then breathe again.
In the event of an emergency, or a crisis, or a time of stress, or a Wednesday afternoon when you feel taken advantage of and under appreciated, or a Saturday morning when all you really want to do is spend 10 more minutes under the covers before facing the onslaught of the breakfast routine, or on your birthday, or on their birthday or any time you need to catch your breath place that oxygen mask over your own nose and mouth first and then assist your companion.