For anyone who needs motivation to do your cardio, I have a little trick for you. I bought a subscription to Audible.com and I ONLY listen to my book when I am on the treadmill or the bike. If you connect listening your book to exercise, you will be more interested in doing your cardio. Voila!
This is really working for me because I am the type of person who would rather have someone to talk to while I do my cardio. I am currently listening to The Nanny Diaries and it is very entertaining. May I add that buying through Audible is much cheaper than buying from Itunes. Now go!