Find Someone Smarter Than You to Learn From
Seems pretty simple but given how busy we all get and all are, actually finding time as a CMO to learn new things and gain some wisdom from someone who's done this before or who has some great experiences to share is a goldmine.
If nothing else you commiserate and laugh about your past mistakes and boneheaded moves. But at it's best you hear how they did something, why something worked, what they were thinking.
It's that part that always gets me excited--what led you to this insight? What was going through your mind? What did you think would happen when you did this? Those questions are where the learning happens for us.
It can be a mentor, it can be a former boss, heck it can be a family member--for me it's often times my dad. He's starting new businesses at the age of 79 and loving his "retirement." I figure that if anyone has gone through something that I can learn from, it's gotta be him.
Find the person--or people--that can fill that role for you. It will make you smarter, it will make you better, it will make them feel great that someone wants to hear from them--and it will more excited about what you're doing, I guarantee it!