Popular advice says that to be successful you just need to follow your passion, which implies that doing something that is driven simply by your interest will be enough to propel your career and financial needs. While it's nice to think that it's that easy, the fact is it's not.

I've worked with many professionals on career planning and development, from executives with 30 years of experience looking to make a change to 20-somethings just out of school looking for their first real job. Regardless of the situation and life phase people are in, the basic formula for career success remains the same.

There are three factors for predictable success. While passion is indeed important, it's not sufficient. Some people get lucky and happen upon two of the factors by chance, but most people are better off taking a hard look at all three when planning their professional future.

1. Internal Drive

People talk a lot about passion, but I find it's often misunderstood. Most times, people think it's something they like to do. And while a true passion is not unenjoyable, it's really not about having fun. What you want to look for is something that drives a lot of intrinsic motivation for you.

Unlike extrinsic motivations--which are the external forces that cause you to want to do something--intrinsic motivation comes from within. It's the fire in your belly that keeps you going strong even when it's hard, when the way is not always clear, and when the reward is not immediate.

When you're intrinsically motivated, you're more likely to invest the time and energy to push through and do the hard work. You also won't be as likely to need external structure and instant gratification to stay focused. This will allow you to stick with the work required for long-term success.

2. True Mastery

They say that it takes 10,000 hours to be an expert in something. At two hours a day, six days a week, 50 weeks a year, that's 17 years to become a true master. And that's what it takes to be truly successful at your chosen profession.

The most sought after professionals are the absolute best at what they do. The trick: They have found a specific niche to be the best in the world at. General lawyers are a dime a dozen. But the lawyer who has mastered the subject of internal maritime law can name his price when millions of dollars are at stake for the shipping company in a dispute.

Choose a narrow domain and learn everything and anything about it. Don't be satisfied with good or even great. Be the best in the world in that niche and you'll be able to not only reap the financial rewards, you'll also be able to control your schedule and choose where you want to work and whom you want to work with.

3. Market Demand

Finally, you need to choose a niche for which there is a reasonable market demand, and that market needs to have sufficient financial means. This niche still needs to be focused, but it needs to be big enough to support your career.

Much of this is relative to your expectations and goals. If you want to make a decent living being a professor of a particular area of art study, then that might be fine for you. But if your goal is to be able to afford traveling by private aircraft, then you'll need to find a niche that pays handsomely for your expert services.

Too often people focus on one, or maybe two, of these factors, only to be disappointed when years of hard work lead to dead-end careers and lack of professional satisfaction. If you're early in your career, the good news is that if you develop a strategy that considers all three attributes, you'll have a much easier time achieving your professional goals.

If you find yourself stuck later in life, it's not too late. Go back and look at these three factors and make the necessary changes. Often, a few tweaks to your focus can dramatically increase your prospects and chances of success.