I find a balance by setting goals for myself. I also keep things flexible. I may not always get to my daily goals. The kids come first, but I have learned over the years that sometimes it is ok to work on my business and let the kids play on their own. If the kids are getting really grouchy, I know it is time to pay attention to them; otherwise, if they are fine, then I know I shouldn't feel guilty getting something done.
There will never be enough time to do everything I want, but it all comes down to our own expectations of what is a perfect life. I have learned to lower my expectations in certain areas and how to meet the demands of other areas.