There's a reason why so few music artists become successful actors (or vice versa).
That's because the world likes to categorize us. And once we establish our personal brand (whether it be in our company, our community or on a much more public stage)...it can be mighty difficult to change.
And yes, we all have a personal brand (although some are more defined then others). So one of the most important decision you can make for your career and your life, is regarding your personal brand: over time, will you expand it's scope, will you contract it, or will you leave it the same?
As we mature in our professions or careers, many are compelled to take on more. It might be curiosity, or just boredom, but many feel tempted to venture into other fields, experiment with different roles, expand the boundaries of our expertise.
But from a purely brand perspective, this can weaken your overall personal brand. As Trout and Reis explained decades ago, the scope and power of your brand, run counter to each other.
Think products. As a clothing brand expands into perfume, not only is establishing authority in perfume going to be tough...just the very act of heading into perfume, can ruin the perceived brand of your clothes.
But I don't think we should necessarily manage our lives like we manage products. So I'm not suggesting the only or even the best thing to do is to focus your personal brand. My only suggestion is to decide in advance. Do it intentionally. Or else the world will decide your brand for you.