In no specific order:

• “Never get puking drunk on tequila.” — My dad, circa 1980 or so; this is advice I did not heed, and I regretted it.
• “Adults are more like children than we often think.” –an editor I used to work with during the early 1990s
• “My mother used to say to me, she used to say ‘Elwood, in this world, you must be oh so smart, or oh so pleasant. For years, I tried smart. I recommend pleasant.” –Elwood Dowd from the movie Harvey
• Living well is the best revenge. –adage
• “Take nothing personally, even if it is meant personally.” –Professor Daniel Baldwin Hess, circa 2000
• “Students never really understand what you are trying to do for them.”–Randy Crane, my advisor

Feel free to add.