"Place the oxygen mask on your own face first, before helping others."
There's a reason the flight attendant says this. Imagine what would happen if you ignored this advice. Your oxygen gets lower and lower, you get frustrated, you fumble...you're not able to function optimally, therefore you're not able to help others optimally; you may even be a hindrance. This is true not just for the plane, but on the ground as well.
When you're in discomfort, you're kinda grumpy, right? Less patient, less generous, less open-minded.... Just think about the expression "HANGRY" - at those times, we know we need to feed ourselves before we transform into the Hangry Monster. We're just not our best until we've tended to our own needs first.
So the next time you think "Argh! There's no way I can get everything done, let alone take care of myself!", remember that you'll be more effective and efficient with others if you start with you . Eat . Sleep. Exercise. Take your vitamins. Schedule a massage- if your body feels better, you'll BE better.