Pretty much the same as the previous responders, we abstain from something that is frivolous and wasteful, and use the time for some act of service for others. I had a Pastor once give up coffee for Lent. That was interesting. ;)
I have given up chocolate before. (This year Lent begins before Valentine's Day and my husband and father's birthdays---all in the next 2 weeks-- so I won't be giving up chocolate).
I am still trying to decide exactly how I want to observe this year. We will start with pancakes tomorrow (Fat Tuesday) and Ash Wednesday services on Wednesday evening (application of ashes to the forehead---from dust you were made, to dust you shall return). Each Wednesday during Lent there are church services on Wednesday evening that we will try to attend. Then, of course, Holy Week has a whole slew of services that lead up to Easter Sunday. (Maundy Thursday, Good Friday, Easter Vigil on Saturday evening, Sunrise on Easter morning).
I am thinking that this year, I may try to avoid being online as much. Maybe put a time limit per day on it. But I have 2 more days before I have to make my final decision about it.