I completely agree that our time is our most precious commodity and often we give it away so frivolously. As an entrepreneur, I have the privilege of working from home on my own schedule and sometimes my friends and neighbours think this means I am available all the time.
I am slowly getting better at saying no, and I have found that explaining what it is I am currently working on allows them to get some insight into my life and makes saying no a little easier. It is all about open communication and being sure to make time for those things you truly want to take part it.
Great article and I look forward to reading more of your work!