The process of maturation requires multiple levels of sacrifice, including what some would call the ultimate sacrifice, putting another's needs in front of your own. This is the role of the parent to the child, the mentor to the protege, and in Christian terms - Christ to the Believer.
Often, people think of the act of sacrifice in terms of loss, but it is just as valid to think of sacrifice as a necessary vehicle to future gain. Without sacrifice, it would seem that the individual is incentivized to search for nothing more than impulsive pleasures with short-term gain and long-term consequence as a result.
What have you sacrificed for the people you love? Having seen the result of your sacrifice, would you trade that sacrifice for short-term pleasure-seeking behavior?