The Correlation between Achievement and Sacrifice
In life there is a basic equation...to achieve certain goals you have to make certain sacrifices....
To look good in that bikini, you have to forgo certain treats such as chocolate cake...or at least moderate your cake intake.
To be a fast or faster runner, you need to log miles, thus sacrificing happy hours and other passive activity social gatherings (company kickball etc.)
To be smart you have to....well, better ask someone else what needs to be done for that category.
Kids fall into this relationship of sacrifice as well. I love being a parent, it has numerous joys and rewards, but it comes with a great deal of sacrifices.
The list is too long to start in on, but you can let your mind wander....