I've been thinking a lot, and I came up with a conclusion. Virtue is just something to make you feel good about your choice. My evidence lies in the fact that, every choice you make, there is a compliment waiting to greet you. Let me give you some crazy examples.

Killing an American - helps the world rid another American - 'jihad'
Killing a Muslim - same reason - crusader

Some less crazy examples:

Standing up for yourself against a bully - being brave
Running away - being the bigger man
Telling an adult - reporting a danger to authority - being responsible.

Do you see that, every time you have a virtue in your favour, there is another waiting to praise the opposite action?