Many people use the terminology that they are sacrificing something for Lent.
We look upon Lent as a time for prayer, fasting and almsgiving in preparing our hearts and minds for the Lord's Passion and Resurrection.
I know that personally, I was taught that you would sacrifice something that you really liked or enjoyed. If I sacrifice, or give up, something that takes my time (watching tv as an example) - I use the time in a spiritual way instead. If I give up something that costs money (a particular food or luxury) - I donate the money to a Catholic charitable organization.
I hope that is an answer to your inquiry!