I am not your typical marketing guy...at least when it comes to my background. I actually was a finance major in college and only took the core marketing class that was required for my degree. I eventually came to love marketing in graduate school when I saw its potential to impact strategy and its ability to draw out my creative side (that was being fueled by music) in a way I didn't imagine could be done in the business world.
I love my quant background and it has served me well over the years as marketing has evolved more analytically and as my positions involved as much business acumen as marketing skill. Understanding the numbers has helped with pricing, statistics, accounting and now analytics. Most of these areas are atypical of most marketing people but the bosses and companies I worked for appreciated that blend of left and right brain thinking and I truly believe it helps me be a better marketer.
The one thing I have to continue to work on is over-analysis - looking to the numbers to show me something I'm feeling but maybe not seeing or looking to make a decision solely based on the black and white numbers when it's not clear. I should never forget that marketing - to some degree - will always live in the shadows and the "feel" of marketing can never be replaced by a black box of data. The creative elements and the customer experience will always go beyond that and instinct and intuition (used in the right context) should still rule the day.
Marketers have to react quickly in today's day and age. The speed by which business moves and the tools we have in place to implement allow us to drop campaigns in a day and receive feedback immediately. The only way to get it all that done effectively is have both parts of your brain firing on all cylinders. Look at the data, turn it into information quickly, act, react and learn from your successes and mistakes. Don't let one side of your brain drag you down from making a decision or make you guy shy about making the wrong one.