I am learning to be very selfish with my time and energy. I should spend it where I want to using whatever system of priority I choose. Sometimes it is just as simple as I want to or I don't want to. Or now is just not the time for whatever for whatever reason.
Don't get me wrong. I am still a reasonably nice person. I will help anyone out if I can. The power comes from knowing when and if I can and how much I can. The power comes from not allowing myself to be sucked dry by doing things that do not add joy to my life. Things that are not required. Things that are better done by someone else. Things that I am not qualified to do. Things that I just don't want to do.
That frees me up to do other things. To do nothing. To do something. To do this or to do that. My choice. To not hold myself to someone else's standard. To spend more time developing my own standards and to live within them.
And the power of saying no leaves tons of opportunity to say yes.