Doing What Comes Naturally

Everyone has something they do really well.  You may not have found this "thing" yet, but there IS something you do well.
This theory works the same in sales.  Our company sells tanks and air compressors.  We once hired a salesperson who had spent his sales career selling tires. After several months trying to sell tanks, he went back to what he was comfortable with: tires.  If you ever notice the sales people in a musical instrument store--for the most part, they're musicians. They're comfortable with musical instruments and music, and they often make good musical instrument sales people.
I consider product knowledge the most important ingredient for a sales person. Therefore, you're going to be good at selling something you want to learn about, something you love.
I am a manufacturers' representative, so I sell multiple products.  I love learning about anything and everything, so this profession worked for me--it was natural.
If you love your product and you love the people who buy your product, you'll succeed in sales.
This rule applies to every type of sales person--from the minister on the altar, to the Sears salesperson selling a washing machine, to a mother in a day care center. I know someone who struggled finding herself until she became a mother--and then she became the best mother because she loved being a mother.  Is she a sales person?  Yes indeed.  She works in day care and mothers entrust their children to her because she exudes "motherness".
Sales is something that's in your soul:  love what you do and do what you love and you can be the best sales person on the planet.