I have been with several different men in different situations recently, and had some discussions about the emotional upheaval they have experienced through past or current separations, divorce negotiations or divorces. The discussions reminded me of what an emotional mess I was during our separation, and how almost non-functional I became at times. I got the essentials of life accomplished, barely, but didn't have much energy for anything else.
I remember an illustration that I saw in the Divorce Care videos that was so helpful to me. There was a picture of an equalizer monitor like you see on a stereo. As the music gets louder and softer on different channels the little indicator goes up and down. The video stated that our emotional energy normally gets pretty evenly distributed between four areas of our lives - physical, mental, spiritual, and emotional. Each section of life goes up and down during normal life but they mostly stay in balance. During separation or divorce though, 85 percent of our emotional energy can go to just trying to maintain our emotional stability and we don't have the energy to accomplish much of anything else. I think from my experience, and from my observations of others in various stages of separation or divorce, the concept is very valid.
Bottom line, if you are in a separation or divorce, or you know someone who is, don't be surprised if it seems like your energy is zapped and it is hard to accomplish your normal life functions of work, play, paying the bills, or exercising.
What helped me more than anything else was getting involved in a Divorce Care group(http://www.divorcecare.org/). I was with people who understood, and I was able to reach out and help those who were in worse situations than I was.