What does it mean to be a great mentor? Mentorship can be a squishy concept, but it doesn't have to be. Allow me to tell you about my friend Bob Wood.

After 28 years as a public-school teacher, Bob reluctantly left the classroom and took the helm of his struggling school. During his 10-year tenure as principal, his team was awarded the National Blue Ribbon by Barbara Bush, a distinction awarded to the top 0.3% of all elementary schools nationwide, and was granted Distinguished School status by the California Department of Education, earning an unprecedented score of 10 out of 10.

Bob has been a mentor to dozens of professionals during his long career in public service. Despite retiring several years ago, he continues to provide guidance to young (and not so young) professionals--like me.

Bob has become not only my mentor but also my friend. He's a natural mentor who has worked with dozens of colleagues and other professionals over the years, so I was honored when he agreed to share his insights regarding mentorship with my UC Santa Barbara entrepreneurial students. Here are the six essential mentor roles Bob described.

1. Taskmaster. "Quality matters. Quality in every endeavor. You're only as good as your last interaction. Good interactions are like money in the bank." Mentors challenge you to reject compromise, especially when it would be easier to take the easy path in the short term. An emphasis on quality makes it easier to commit to your goals.

2. Coalescer. "Once you're in, you're fully in. Whatever you do, don't waffle." Mentors do not allow you to hedge pivotal decisions. They force you to explore the facts and pursue a definite path. Their unwavering confidence in your abilities fortifies you with the resilience required to not only make bold choices but to see them through to fruition.

3. Provocateur. "All mentors have encouraged me to be risky. They certainly didn't get there by not taking chances." The guidance of someone who has walked the path you're currently taking puts seemingly daunting risks into their proper perspective. Your mentor's experience will embolden you when assessing the potential outcomes of key decisions.

4. Preceptor. "Being knowledgeable, there's just no way you can fake it. Know the business...inside out. You need to have that whole package, or build it by connecting with someone who can assist you in those areas [where you're] weaker. Mentors have gifts in areas you don't. You learn by being with them, walking with them, talking with them, hanging out with them." Great mentors are great teachers. They freely share their knowledge with you and encourage you to become a life-long learner.

5. Sherpa. "Approach things with the mind of a beginner, so you're seeing things with fresh eyes. When you're going through changes...it's a little bit like being an anthropologist. You're trying to make sense out of a new situation and you don't have this mindset of parameters that are limiting your thinking and what you're seeing." Assume that you don't have all the answers. A mentor reminds you to wake up when your assumptions cloud your ability to draw insights from new information and experiences.

6. Champion"Mentors can be cheerleaders in times of transition. Someone you can trust and confide in, in this sometimes cold world. Loyalty... it's a two-way street. Basic commitment. I'm there for you, you're there for me. No ifs, ands, or buts." Healthy mentor relationships are not conditional. Each party respects and appreciates the other, even when one of them makes a mistake.