Kathryn Schulz absolutely nails it:
(Hat tip Saganist and Jon Adams)
This is one of the biggest things I've learned in my life: it is inevitable that some of the things you believe are wrong.
A lot of it is due to invisible assumptions -- beliefs you hold without even realizing you hold them because you've never really consciously noticed them. (Here are some past posts where I learned from new experiences and by noticing my own invisible assumptions.)
Even on questions you've spent some time thinking about (and have reached a conclusion), it's important not to get too emotionally attached to your conclusions. Always be ready to question your conclusions when presented with new arguments or new evidence. (Here are some posts where I learned from my own errors and reconsidered my conclusions.)
There's no shame in being wrong (even publicly) and admitting to it. Refusing to ever recognize or admit your own errors -- dogmatically fighting to the death to back all your past statements to avoid ever having been wrong -- (ironically?) makes you less credible, not more.
It's how Science zeroes in on accurate results, and it works on a personal level too! :D