I teach psychology classes at a local college, and one topic that I cover in my classes is Type A and Type B personality. Type A personality is more rigid, more controlling, and more anxious. Their response to stress is impatience, and competitiveness. Type A personalities are notorious workaholics. It's not surprising that people who are Type A are at twice as much risk of a heart attack. On a brighter note, these personality traits are highly valued in a professional society, and may help promote an individual's success.
Type B personalities, on the other hand, take a relaxed approach to life. They are more laid back, and they handle the daily hassles of stress much easier.
Most of us are somewhere in between Type A and Type B. I see Type A tendencies in myself (for example, my refusal to miss a single day of blogging in an entire year! I mean come on, let it go already!) but I can also be very laid back about some things (like if the kids stay in pjs all day...or wait....is that just lazy?). Realizing where you fall on the spectrum may give you a self-awareness to help you handle various situations you encounter in a normal day.
Do you know which one you are? Want to take a test to see? I often refer my students to THIS site to find out. If you take the test (it's fairly short), come back and let me know how you scored!