Grappling with the idea of Sacrifice...

It was to be the week of Sacrifice, a week ago. A little rushed in general and a ways behind on the previous virtue in trying to imbibe it more completely, I was quite frankly just stumped. Is Sacrifice a virtue? And why, if so?
How is sacrifice different from the act of giving, of oneself even? How is it different from abstaining from that which is excessive or to be eschewed for a larger good? How is it separate from the actions of one acting in complete detachment? Is sacrifice to be viewed as distinct from austerities for self-discipline and development? Or is it perhaps a broad umbrella for some or all of these? Why can I only think of martyrs who gave up their lives for freedom movements, or humanity?
How does one sacrifice and what must one sacrifice?
Some initial readings produced very interesting and varied notions. Striking among them, as usual, in its intensity and severity was Ayn Rand's opinions here. I shall pen my thoughts on this subject as I clarify them more...