APTITUDES
According to the fine research at the Johnson O'Connor Research Foundation, identifying and then utilizing your aptitudes is essential for feeling good about life. If they go unused, there is a vague sense of discomfort. If you use them, you'll also be more productive and like whatever you do.
I had a 99+ percentile "Ideaphoria" (the flow of ideas) aptitude and they advised me to avoid being in an executive position, where I would have to execute and would not be able to utilize my great creativity. I would have been stressed and frustrated.
SIGNATURE STRENGTHS
A term I first read about in one of Martin Seligman's great books. See his Authentic Happiness book. Link to his site, get a password and then take the tests. Use those strengths as often as you can, as they are a form of true self-expression.
A signature strength is moral/values related. They are a strength of character.
It is of the nature of integrity, valor, creativity, kindness. The other strengths that they use are curiosity, critical thinking, open-mindedness, good judgment, love of learning, perspective, bravery, courage, perseverance, persistence, diligence, industriousness, honesty, authenticity, zest, love, generosity, social intelligence and skills, fairness, leadership, forgiveness, modesty, humility, prudence, self-control, appreciation of beauty and/or excellence, gratitude, optimism, playfulness, humor.
TALENTS AND CAPABILITIES
Identify what is "easy" for you to do (and which you often discount as no big deal. Use those talents and capabilities in your work, as they make work more enjoyable and easy and rewarding.
In Living 80/20 and in the Productivity section, we learn to identify our Unique Capability - and once we begin to use it the amount of money made and/or satisfaction or whatever you are trying to attain increases dramatically. Read about this on Dan Sullivan's site: StrategicCoach.com and in his book "Unique Ability: Creating The Life You Want". A "unique capability" is one that is where you perform at a level beyond even your "excellent" abilities, which others can provide instead of you. If you use your unique capability over and over, you'll multiply your success above even the leverage that is provided by your using your excellent abilities - and life will be alot easier. It is definitely in alignment with the 80/20 Principle!
RELEVANT RESOURCES
Combining the above, the best selling book Strengths Finder 2.0, by Tom Rath is the recommended one in most experts.