Oh, I remember I was so stubborn that I didn't want to give up on a particular client with whom I've been working for years.
He was asking me to send in the work on a weekly basis. I had my baby on a Friday night. And I realized I completely lost the notion of time during the first week. I was forced to take a step back and tell the client I couldn't handle it.
Still, it was a shock for me to see just how little from what I used to do I was able to do while caring for a newborn.
I think even if we would be warned about it, we would still not be able to understand it until we're already involved with no way of return :D
You just can't imagine what it's like for someone to depend with his life on you, until that very thing happens.