When many of us were kids, there were perhaps many things we wanted. From as material as a new toy to basic needs like food or affection. We grasp the things we have tightly (sharing is universally such an important lesson for children) and reach out for more around us (like a monkey grasping onto nuts in a pot). It's a stage characterized by exploration, but maybe also by entitlement and selfishness.
At some point, we begin to work to gain things. We take things we have (work ethic, money, education, skills, time, physical ability, resources, connections, health, etc.) and exchange them for things we need or want. Depending on what is being gained and the person, this happens earlier or later for different people. A necessary step in understanding the value of things. With the awareness of value and cost, we tend to hold on more tightly to our things, to our beliefs.
In the third "post-sacrifice" stage, sacrifice is an already accepted habit. When the time comes to sacrifice, it's not a personal loss if we start from the premise that it's not ours to begin with. Anything sacrificed is simply something not gained, and anything not sacrificed is a welcome prize. We acknowledge the effort that we and others put into things. Letting go enables us to pursue greater and more meaningful things. Yet we must not forget the lessons of fulfilling our needs and valuing what we have.
Getting from pre-sacrifice to sacrifice stage takes work. It's a grueling and not altogether pleasant experience.
Getting from sacrifice to post-sacrifice is not usually something that can be forced. It takes life experience in various domains. There may be things we can do or practice to make the transition more likely, but mindset changes can't just happen overnight nor by force of will.
Moving from one stage to the next may not occur together. We might be willing to sacrifice in one area, but entirely stubborn in our ways in another.
Forward movement may not be permanent. The earlier stages are much more deeply ingrained habits, which we often slip back into in moments of stress, distress, or excitement.