Definitive Generosity???

I have been the last few days about the idea of generosity.
As usual, in my ponderings I've only come up with questions...

What is generosity really?
It can't be just giving, can it?

If you give something but you can afford to give it, is that still generosity?
ie. I can afford to buy someone lunch at Wendy's without missing the money, it really isn't costing me anything. But what if I wanted to buy someone a 5 course meal at an expensive restaurant, and I had to do without in order to treat them...does that count as generosity because it costs me?

It is the cost that makes it generous or not generous?

Or is it the intention that counts?
Lots of businesses give because it makes them look good in the eyes of the public...is this still generosity, even though it has a self-centered interest at heart?
Charities would suffer without corporate sponsors...so there is value in it...but is it generosity of heart or a just a tax right-off?

Is generosity defined by the gift, by the thought, by the intent of the heart, by the amount?

This might sound like a stupid question to some, but I've really been thinking about this and wondering how to teach generosity to the youth I work with, and to my kids. In thinking about this, I must first define it for myself before I can teach such a concept.

My second thought is this, isn't the best way to learn to be generous by experiencing generosity yourself? Should I just give and hope they will follow my example? What would be a good incentive for a teenager to want to be generous to another human being (especially those who feel like the whole world is out to rip them off)???

Questions, questions, questions....