The Art of Free Time

A friend of mine asked me the other day whether with two kids I have any time to do anything for myself. I said of course I do.
Then I thought, then how come I never get anything done?
Today for a rare hour of the past 6 months my children and husband were asleep in the middle of the day leaving me time for myself to do whatever I want without me being too tired.
Because it was the middle of the day I had so many things that I had to do and some things I wanted to do.
I could wash the dishes, fold the laundry, pick up the toys and finish cleaning the house. I can study something. Write something. Read one of the many books I started and never finished. Pop in a movie. or Write. By the time I decided that I would make myself something warm to drink and relax with a book, my son woke up. and free time was over.
Is it that time isn't enough? or like everything else the more organized you are the more you can squeeze things to do in a short amount of time.
Time is a blessing and if your time is blessed it seems to be stretched.
Now I sat around just to relax and it is already late and so many of the things I wanted to finish before I sleep are still left undone.
Tell me. How can I master the Art of Free Time?