Using functional Magnetic Resonance Imaging to detect neural activity, researchers have found that the stated details about something have a greater impact on how we appreciate something than the actual thing itself.
In one experiment they showed subjects both authentic paintings and copies, before the image was displayed, an announcement was made indicating whether it was real or fake. But, half the time they switched the labels so subjects were looking at a real painting, but told it was fake. The difference was all in the label and not in the real thing. Again wine connoisseur were given sips of wine while in an fMRI and told the price of the vintage. They weren't told, however, that the same wine was reported to have different prices so they stated a preference for the more expensive wine, even when it was exactly the same.
The consistent factor here is the orbitofrontal cortex, it lit up when the expensive wine was tasted and the authentic paintings were viewed. This region of the brain is most often associated with reward and monetary gain. People perceived the label in the same way that they would perceive any other reward, so they assigned greater value to the thing. Value that wasn't inherent merely attributed, yet the brain filled in the gaps and acted as if the object were just as valuable.
So, say good things. Charge more money. Act like what you do is valuable. If you deprecate your time, effort and output verbally, then others will do the same mentally. But, if you assign labels of value to what you do, others will perceive it as valuable.
What ways do you devalue yourself and your work? How could you change that?