“Sit in this corner until you can stop thinking about a white bear.” Said the older brother of a young Leo Tolstoy, the Russian novelist.
Several hours later the brother returned to the room to find Tolstoy paralyzed; still in the corner and unable to stop thinking about white bears. 
Why couldn’t Tolstoy stop thinking about white bears? It’s not like Russia was dealing with some massive white bear epidemic at the time. So why couldn’t he get the thought out of his head?
TRYING TO SUPPRESS OUR THOUGHTS
Over a century later, Harvard psychologist Daniel Wegner set out to answer this question. He invited participants into a lab and asked them to think about anything other than a white bear. The participants had about as much luck as the famous writer of War and Peace. No matter how hard they tried, they just could not stop thinking about white bears! 
As I’m sure you can guess, this phenomenon is not just subject to thoughts about White Bears. Wegner repeated these studies trying to get participants to suppress other thoughts. Unsurprisingly, no matter what the thought was, the participants were unable to suppress it.
And it didn't stop there. Even more shocking is that when they suppressed something, they ended up thinking about it more than if they were actually trying to think about it!
Wegner called this phenomenon “Ironic Rebound”. It explains that the very thing that we try to not think about rebounds back into our thoughts without fail. This explains why denying foods can leave dieters more tempted to indulge, why someone who’s nervous about a big speech ends up imagining the worst, and the catchy song we’re trying to get out of our heads ends up playing on repeat.
WHY CAN’T WE CONTROL OUR THOUGHTS?
When we’re trying to suppress a thought, we send a message to both our conscious and subconscious minds not to think about it. The conscious mind will then attempt to direct your attention elsewhere – trying to distract you from thinking about it. Meanwhile, your subconscious mind gets the message to be on alert for anything that might make you think about that thing.
Unfortunately, through this process, the subconscious mind holds the very thought that you’re trying to suppress with it, because it’s looking for anything associated with it. 
For example, say you’re one of the participants who has been given the task of not thinking about a white bear. Your conscious mind is now trying to direct your attention to something other than a white bear.
So you pick up a pencil and focus on it. At that point, your subconscious mind sends the message to your conscious mind, “hey look, a pencil! That’s not like a white bear at all!” Thereby making you think about white bears again as you marvel at how much the pencil is not like a white bear.
WHAT THIS MEANS FOR WILLPOWER
One of the biggest things we use our willpower for is self-control. We want to control our diets, our tempers and our credit card debt. Unfortunately, due to ironic rebound, the more we try to control our thoughts of Ben & Jerry’s, that annoying coworker or the one-time-only sale at the mall, the more likely we are to lose that control.
Even if we do end up resisting the temptation, the process of trying to control the thought is going to unnecessarily burn through our willpower, leaving us more likely to indulge in something else. 
SO WHAT CAN WE DO?
Give up. That’s right, the tactic that Wegner found was most successful in controlling the thought is to actually give up control of it. When he allowed participants to express or think as much as they wanted about the thing they once suppressed, they were able to move on to other thoughts and feelings much more easily. 
Now, this doesn’t mean that we should act on these thoughts. Quite the contrary. If you’re tempted by the donuts somebody brought to the office, don’t try to suppress how much you want to indulge. That will leave you craving the donut the rest of the day. Instead, embrace the feeling of temptation.
Understand that your inner feelings do not dictate your outer actions. You are in control of yourself. So allow yourself to want the donut (that's natural!) but understand that you don't have to act on that craving. That way you can walk away from the break room and go back to your desk without the long day of trying to not think about the donut.
Trying to suppress a thought is doomed for failure. So often we try to control our thoughts of temptation, anxiety or secrets that we’re supposed to be keeping. But the more we try to suppress these thoughts, the more likely they are to keep popping back into our heads.
Instead, allow yourself to think about these things. Embrace the thought, but understand that you still have control over your actions. In the end, we always have the choice of whether or not to act on our thoughts, emotions and feelings.
- Wegner, Daniel M., and David J. Schneider. "The White Bear Story." Psychological Inquiry 14.3-4 (2003): 326-29.
- Wegner, Daniel M., David J. Schneider, Samuel R. Carter, and Teri L. White. "Paradoxical Effects of Thought Suppression." Journal of Personality and Social Psychology 53.1 (1987): 5-13.
- McGonigal, Kelly. The Willpower Instinct: How Self-control Works, Why It Matters, and What You Can Do to Get More of It. New York: Avery, 2012.
- Winerman, Lea. "Suppressing the 'White Bears'" Monitor on Psychology 42.9 (2011): 44.