Why do we do what we do?

I just read an article that asks, "How do you know when you've found something you are passionate about?" If you answer "yes" to most of these questions, you're probably on the verge to finding it.

• Do you lose track of time doing this activity?
• Do you get excited just thinking about it?
• Do you feel energized by it?
• Do you dream about it?
• Do you lose self consciousness doing it?
• Do you perform beyond your usual abilities when engaged in it?
• Has your enthusiasm remained high over a period of time?
• Do you seek out people who share this interest?

Hmmm, sound familiar show people? But I guess these attributes could also describe a drug dealer.