Best thing I've ever read on what to give up and the correct attitude about it. Favorite parts follow, but you should read the whole thing:
If you want to lose weight or quit smoking, do it on your own time. [emphasis hers] Lent isn't about looking better in your jeans or avoiding emphysema, although we wish you the best on both those counts.
Lent is about giving up something that will be a daily reminder of the fact that it's Lent. Then while you're thinking about the fact that it's Lent, maybe you'll remember what Lent is all about.
And don't try to sidestep your plan. If you've decided to eat your oatmeal plain, with no brown sugar or milk or raisins or anything, and then you eat eggs half the time for breakfast, shame on you, you slacker. No one let up on Jesus.
Yeah, you slacker! You go, Sister. People who try to give up cigarettes just end up being grumpy and becoming a mortification to everyone around them. This is serious advice from a spiritual offensive coordinator, delivered straight, no chaser. You want to get to Heaven don't listen to me, listen to Sister Mary Martha.