Christopher Hitchens in his book god is not Great addresses impossible tasks put forward in the Bible.

“The order to ‘love thy neighbor’ is mild and yet stern: a reminder of one’s duty to others. The order to ‘love thy neighbor as thyself’ is too extreme and too strenuous to be obeyed, as is the hard-to-interpret instruction to love others ‘as I have loved you.’ Humans are not so constituted as to care for others as much as themselves; the thing simply cannot be done.” [p 213]

The obvious answer to that is: just because a thing can’t be done shouldn’t mean it is not worth striving toward, however, taking it as a command and feeling like a failure when falling short would be a mistake.

My answer is a bit different. I agree with Hitchens that we are not constituted to care for others as much as we care for ourselves. I firmly believe we should care for ourselves above all others. Here is the step that makes self-love work for me. To care for myself, I need to know myself. To know myself I need to think about what makes me happy and what makes me sad. I have found that it makes me happy to make others happy and that if I make another sad, it makes me sad. So there you have it. If I make you smile, if I give you something nice to think about, if I give you a fond memory; it is purely selfish on my part.

PS: I recommend god is not Great for more evidence that Satan wrote the Bible, though, to be sure, Mr. Hitchens does not believe in Satan any more than I do.