That's awesome for your aunt. It's something I am going through too, so I'll tell you what works for me and maybe it would work for your aunt. I read a great article about smoking in the latest issue of SELF magazine (with Drew Barrymore on the cover) that seriously made me want to quit!!! So maybe show her that for "inspiration."

More inspiration/help breaking the habit (it's working for me, anyway):
-Add up how much money she'll be saving in a year by quitting smoking
-send her to quittobacco.org
-see if you can find her a quit smoking discussion/support group in her area
-get her something to play with or hold in her hands, like a rubbing stone, a handheld video game, or some needlepoint/sewing
-buy her some gum or hard candy to chew on/suck on
-look for some other way for her to reduce stress (you said you're exercising together, which is awesome. Yoga, pilates or massages work for me!!). Cleaning, cooking, meditation, sleep.

Every day she is off the cigarettes, the moodiness will get better and better. If she can make it through the next 4 days to a week, she'll have made it through the roughest part. Just your being there for her is awesome!!

Let us know how it goes!