As Parkinsons Law states, Work expands so as to fill the time available for its completion.

Along with deciding what jobs/clients to accept or dump and how to charge & bill properly, this was in the list of the hardest lessons of consultancy I had to really learn and understand.

For a very long time, I was perpetually stressed because there just was too much to do in any given day; and it didn't matter if that given day was 5 hours, 8 hours, 12 hours or more.

The big realization? If you are good and in demand, there will always be more to do than you will have time for. This is actually good fortune. So get over it!

Prioritize what needs to be done and do it. What doesn't get done today will have to wait. If you are still getting more business than you can possibly handle, it means your rates are too low. Raise them, lose some business that you can't get to anyway, make some more money, and get some of your life back. You'll be less stressed and happier.