I gave up silly shit like giving things up for Lent a long time ago.
I did the same about seven years ago. After 40 days, I realized I was doing just fine without, and have kept the habit kicked since then (no nun pun intended!).
Oh ye cranky people, think of it like the procrastinator’s New Year’s resolution. 
Myself, I intend to give up laziness. I’ll do my laundry every week like a good ninja, I’ll work out every morning for at least half an hour, I’ll keep my room and car clean…
I wonder how long this is going to last. 
I’m not giving anything up, per se. In the true spirit of the season, I am going to spend the next 40 days in serious introspection, hard work (both in school and at my job) and, eschewing frivolity for my own enjoyment, give time and treasure to help the poor and downtrodden. I will focus my energy and talent (such as it is) on becoming a better man.
Mutual support and accountability, maybe? In response to Mangetout. If I’ve publicly announced I’m going to do something it makes a little more likely to actually do it.
I’m giving up abstinence.
Desserts, soft drinks, and everything else with lots of artificial sugar.
Since we’re posting anonymously, it’s not an anouncement.
I was raised a Presbyterian (that’s a protestant with presbyopia.) We didn’t do this ritual. What’s the point of giving up something for Lent? On Tuesday, you have wild revelry and untrammeled sin, then on Wednesday, you give up something until Easter. What is it supposed to mean?
Catholicism
Probably roasted peanuts in the shell, as they are my absolute favorite snack. Seriously, this is a big deal for me. I’m already mourning their departure from my life for a whole 40 days. 
Except that we do actually know each other a bit here - even if only virtually - so it’s not real anonymity. I liked Lissla Lissar’s reason better.
Last year I gave up TV. It was one of the most liberating things I have ever done. I suddenly had time for prayer, I had time to drive for meals on wheels, and I had more money to give to the Heifer Project. Those are the things I sorta expected. The thing that surprised me most was this changed my conversations. Since I couldn’t talk about what went on on Lost or 24 my SIL and I ended up talking about our feelings and experiences with OCD parents. My friends and I couldn’t talk about Stargate, etc. so we ended up talking about books (still science fiction), problems and brainstorming solutions about elderly parents, and one very hairy conversation on child sexual abuse and what it was like to be raped (that conversation started with “Damn Reepicheep, when can we talk about House again”.
I kept it off til my best friend visited me in November, and she “needed daily news”, and I got hooked again. I’m giving it up again this year.