Instead of giving up chocolate (again) how about saving someone's life? Last year I joined 40 Days for Life during Lent and it has changed my perspective on a lot of things. I go to an abortion clinic once or twice a week (or as often as I can make it) and pray. If you find it hard to get to a 40 Days site, you can still participate by fasting and/or praying along with their set of daily devotionals.
Another way to get involved this Lent is to spiritually adopt an unborn child. To do this, pick an unborn baby in danger of being aborted. It doesn't have to be anyone you know, just focus your intentions on a single child. You can give the child a name if that helps you to focus on him or her. Each day pray for this child. Bishop Fulton J. Sheen recommended the following prayer:
“Jesus, Mary and Joseph, I love you very much. I beg you to spare the life of the unborn baby that I have spiritually adopted who is in danger of abortion.”
Of course you can (and should) pray for the mother and father of that child as well. These things are simple enough to do, and yet they can save a human life, and change yours.