I used to hide my autism whenever humanly possible; I would only disclose it to others under extenuating circumstances (e.g., needing exam accommodations in college). I'd constantly feel anxious over whether anybody would find out...and how they'd treat me, if they did find out.

Now, I just tell people. I'm upfront about it because I've learned that it just helps people understand (or try to understand) me better -- whereas, when I've tried to hide it, people would still pick up on the reality that I'm "different" (despite my best efforts to hide it), and, therefore, it would only cause their perception of me to become confused and/or mind-boggled.