Weight loss regimin for needy friend! Help!!!!?

I am a very athletic 29 year old male. I have always played sports and I consider myself to be in pretty good shape. In seeing this, I have a coworker of about 8 years ask me to help her lose weight and only feels comfortable in asking me because we have become very good friends. We will be joining a gym together next week and is too embarred to ask a personal trainer to get her on a regimen and asked me to do this for her instead since she is comfortable with me and would use me as inspiration. Any ideas on setting up a weekly regimen including cardio and weights? she is about 100 pounds overweight and i would love to help her out.