Your work is going to fill a large part of your life and the only way to be truly satisfied is to do what you believe is great work. And the only way to do great work is to love what you do. If you haven't found it yet keep looking. Don't settle. As with all matters of the heart you'll know when you find it.
If you asked an 18-year-old what they want to do with their life and the options are 'Transformers' or Lars von Trier he's probably shipping out for 'Transformers.' If you ask a 26-year-old what he wants to do 'Transformers' or Lars von Trier he'd probably pick Lars von Trier. So my sensibilities are changing as I change.