I recently heard a helpful analogy. If we consider ourselves to be like a traditional china tea cup, then we should be caring for others out of the overflow that spills into the saucer, not pouring out the resources inside the cup until we are empty.
Often when this topic comes up in conversation (especially with women), I have heard people say, “but it feels so selfish to be putting myself first and spending time and resources on me. There are so many other demands, the people I love need me, and I tend to put myself last, if I ever get around to myself at all”. I catch myself saying the same thing sometimes. I will get around to taking care of me later…