We've bought into the myth that if we give and give and give, deplete our resources, and keep going, we somehow earn a special badge of honor (cue the chorus: "I don't know how she does it!").
The Facts: See above (myths #1 and #2). It's all the same mindset and the same facts. It's so deeply ingrained that sometimes we can't see it, so it's worth repeating. My dear, you can be so much more potent and effective when you fill yourself up first. Trust me, it's not selfish! You may very well be doing it all. But how well are you able to do it and for how long? More importantly, at what cost?
The thing is, I believe in you. I believe you can do it all... just not all at once! Because that would be super-human... you, lovely lady, are a human with super-powers (there is a difference!).