To "have your cake and eat it too" can be simply translated into, "you can't always have it both ways," as I understand it.
As I type this, I am sitting at my computer desk, wondering about what life has in store for me. What am I to become, what will I accomplish?
I want so many things in this life. I want to lead a guild in WoW, but I also want to follow a leader. I want to be a teacher, or a psychologist, but I also want to be a small business owner. I want to live in America, but I also want to live here in Australia. So many choices, so many appetizing looking slices of cake, I'm not sure which to choose.