As I packed for my tournament in Orlando, I was trying to squeeze all of my clothes into my suitcase without breaking it. When i pushed down on it, the suitcase pushed right back up at me because I had so many clothes stuffed in there. When I thought about it, the suitcase acted like a spring!
A spring compresses and then expands just as my suitcase did. However, there is no "constant" within the suitcase as there is in a regular spring. The suitcase also required me to do work. I had to use energy in order to close the suitcase but at the same time, the suitcase was also doing work on me. Every object presses back on the other object with the same magnitude therefore, the suitcase did work on me. There is physics in everything!