How many times has someone invited you to their meeting, happy hour, coffee break, tea break, lunch break, lunch meeting, round-table, panel discussion, working group, group vacation, hiking trip, dinner party or retreat (whew!) and you find yourself dying to say “I’d love to, but I have to teach my fish to read”?

While you’re deliberating whether or not to tell a less outlandish lie in an effort to retain what’s left of your free time that day, week, month or year, the guilt eats at you until you reluctantly click “going” or “accept” on the invite. Not long after you do, another parasite probably starts to feed: resentment. You find yourself looking at a calendar that is jam-packed with events and you start to loathe (but not really … right?) the people who asked or demanded to occupy the blocks of time scattered around your calendar like invasive mushrooms.

You start spending almost as much time in transit as you do stationary. You start losing sleep. Your stress level starts to rise. You stop working on the projects you really enjoy. Eventually you start to quietly wonder whose life you’re living, because it’s certainly not the one you wanted to live when you started out that day, week, month or year.

If this even remotely describes you, ask yourself: When was the last time you said “no”? And, no, “I’ll think about it” or “can I get back to you” don’t count. When was the last time you told someone who asked for your time “no” in all of its unforgiving glory?

When you didn’t say “no,” did you acquiesce because you thought it would bring valuable experiences into your life — experiences that might fuel your creativity and make you a more valuable, productive member of society? Well, that assumption may be erroneous. As Drake Bauer writes for Fast Company, one of the keys to productivity is an empty calendar.

“If we want to do the work that we want to do,” he writes, “we need to own our time — how else can we spend it productively?”

His piece, which will take up very little of your time to read (if I may be so bold as to suggest how you should spend your time, given the topic at hand), is worth it if only for encouragement to face down that next invitation. Bauer’s piece points to an even better (and moderately short) read from Kevin Ashton over on Medium, which nicely explains the value of “no” in creative people’s lives. Ashton writes:

“Time is the raw material of creation. Wipe away the magic and myth of creating and all that remains is work: the work of becoming expert through study and practice, the work of finding solutions to problems and problems with those solutions, the work of trial and error, the work of thinking and perfecting, the work of creating. Creating consumes. It is all day, every day. It knows neither weekends nor vacations. It is not when we feel like it. It is habit, compulsion, obsession, vocation. The common thread that links creators is how they spend their time.”

So, in order to have that time to create and become one of the “many up-all-night successes” Ashton refers to, try saying “no.”

No to the meetings.

No to the lunch breaks.

No to the coffe breaks.

No to the happy hours.

No to the parties.

No to the book clubs.

No to the retreats (where you don’t really retreat).

No. No. No.

That said, as Forbes contributor Margie Warrell writes, stress and stepping outside of your comfort zone can be valuable in terms of improving your productivity. But there’s something to be said for having those experiences on your own terms rather than someone else’s.