I’m a little wiser now. I know I’ll never find a perfect balance between the professional and the personal, but I’m committed to trying. I know that much of my time will be devoted to my career, but I need the work to give me something back in return. I want to be surrounded by people I can learn something from, and I want to make a difference.

Mentoring is often given lip-service in business, but it’s not always experienced in reality. Still, I’m looking for people from whom I can soak up character, judgment, approaches. They don’t have to be bosses-in fact, I’ve learned just as much or more from peers or even subordinates. How people act in tough situations has taught me a lot. I remember how one particularly strong mentor handled a period of turmoil. At the time, some meetings had become shouting matches and the emotional investment required to hold them together was so intense that, holed up in the office, this person would occasionally break down and cry. I learned a lot from seeing my manager pull it together to continue to manage effectively, despite the emotional stress.

As new Yahoo! CEO Terry Semel said the other day, “Why am I here? [It’s] the whole idea of being a part of something conceived to change the world.” It is the same for me. The potential to make a difference-more than coffee or anything else-gets me going each morning. I first really got excited about genomics during an interview in a Palo Alto restaurant. As we talked, we scribbled on paper napkins possible ways to use the company’s new “DNA chips,” tiny squares of glass coded with DNA that help determine which genes cause diseases like cancer.

At the time DNA chips were brand new, and the company only had two real customers. Today, hundreds of customers are using these chips to improve drug development and health care. Building up the business was hard work: some days, it left me overwhelmed and exhausted. But the technology’s potential kept me coming back.

So what are the best criteria for picking my next job? Issues like what I’ll be paid, where I’ll live, and chances for promotion are certainly important. But if I can figure out what really matters to me, everything else will fall into place. I’ll let you know.