Marie... you can do your affirmations and visualize at any time. The more the better. If you need quiet time you can add meditation.

The one thing I truly believe is that affirmations work much faster and more effectively when you are passionate about them. If you feel energized and passionate while on the cardio machine, by all means, do it.

By the way, I have to agree... it's really hard to not feel like you are making a difference while you are exercising.