The key to weight loss: "It's all about intensity. If people really want to lose weight they must exercise vigorously for at least 20 minutes, five days a week, in what I call 'the results zone.' That is, on a scale of zero to ten you should be exercising at a level 7 or 8.

Your breathing is deep and you could carry on a conversation, but you would probably prefer not to. Be sure to work up to this level gradually. It may be a good idea to exercise with a qualified exercise professional for at least your first couple of sessions."

On exercise and health: "Physical activity today is like smoking was 30 years ago. People know exercise is important to health, but too many are still not doing it. Society is just starting to get behind efforts to encourage everyone to exercise."

Karen Voight trained in ballet for 20 years, has been named "Fitness Instructor of the Year" by IDEA: The Association of Fitness Professionals, is the founder of two California exercise studios, creator of eight fitness videos and author of Voight: Precision Training for Body and Mind.

What works: "Find an activity you like, so you can look forward to your workout as a chance to play and relax your mind. Be present in the moment and enjoy what you're doing as opposed to thinking, 'I'll get through this'."