atheists can give things up. It's no bad thing to be able to demonstrate that in control of your own life, you're not a slave to habit nor addicted to anything.
At church on Sunday our minister suggested that rather than giving up anything, perhaps we could all give something. A wee prayer for family/friends, a few coppers in a collecting can, a bunch of flowers to a friend etc etc. Sounded sensible to me so I have said a wee prayer today for all my friends/family including my "on-line" ones.