dr. marc seigel about her battle against cancer and multiple sclerosis. >> how has having chronic illnessnged your life, your identity, how you look at life? >> it certainly does change your perspective on life. i like to say m.s. has been my greatest teacher. cancer was also another great teacher. sometimes i wish i didn't have quite so many wonderful teaching moments in my life. but it does teach -- help you be aware of others that are suffering. for me, i think that the biggest lesson i learned from both having cancer and from having m.s. is compassion for others. >> what about the fear of being sick and the stress? how do you cope with both negative emotions? >> it was a very dark time in my life when i was first diagnosed. i went in to a pretty dark place for a long time. i think that the thing that happens is that when you have a disease like this, it takes everything away from you, for instance i was weak and fatigued so anything i was doing in my normal life i could no longer do. then the rug is pulled out from underneath you an you are left with nothing, you go through a phase of