If you've ever had to complete a long-term project (read years)--you already know what its like to have obsessive thoughts. If you've trained for a marathon--you've engaged in compulsive behaviors. And if you've been in love--you definitely experienced obsessive thoughts and compulsive behaviors.
That's not a problem. Creating art and pursuing a love demands such focused and sustain efforts. Your thoughts and behaviors are not always going to be pegged between such narrowly defined markers labeled "normal" if you're to achieve greatness.
Or if you prefer you could say that normal is a wide range of thoughts and behavior with problems occurring only at the extreme ends of the continuum. It's only when you experience significant discomfort or are disturbed by your own thoughts and behaviors (or others are so upset with your behavior it bothers you) that they become a problem.
Maybe your obsessive thoughts and compulsive behaviors are a deeply ingrained part of your personality. You feel better when you act on those thoughts and behaviors and generally they don't cause you much problem. You've earned the stereotypical "neat freak" label because you're the one who always cleans the microwave and sink at work or color-code your socks
When your thoughts/behaviors fall into the category of Obsessive-Compulsive Personality Disorder, they have moved significantly away for the usual behavior of those around you. They also cause you real discomfort. This may include extreme perfectionism, hoarding that has really become a problem, and being quite inflexible in many of your behaviors. While difficult to change, being aware of the problem and exploring ways to strengthen your coping skills and trying new behaviors will help you limit some of its more negative side effects. The goal is to take advantage of the benefits while limiting the negatives.
Obsessive-Compulsive Disorder Is a more severe form of this condition. Here individuals engage in time consuming or elaborate patterns of behavior that they realize are no longer logical or helpful. Most importantly, the individual suffering this condition is unable to control these behaviors. Specific behavioral therapies are useful in helping with this condition and there are medications that have been effective in alleviating its symptoms.
The goal is not to pathologize normal behavior, but also not to ignore real suffering or the help that's available. Help that can bring you relief and increased quality of life.
When have you been obsessed with an idea? Have you been so committed to goals you felt a compulsion to achieve them?