"Set up an appointment with a trainer or a class that you have to go to, because most people do things that they have to do. For instance, going to work - how many of us would go to work unless we had to? So you can't wait until you want to do something. It's almost like walking into a room full of weights and saying, when I get strong, I'll lift those up. You have to go do it and that's how you get strong," she said.
Dr. Donnelly also recommends you find somebody who will hold you accountable.