How can I start eating proper meals?

I once saw a lady on tv who was eating junk food all day and every day, and the solution, which I suppose was a temporary one was to put the initial emphasis on the type of food rather than the quantity. So instead of her pigging herself on chocolate and soft drinks at lunch time, she would make an equal pig of herself with fruit and vegetables. In my own case, I know I eat too much chocolate and I want to switch to fruit but the problem is being prepared and having enough fruit in the right place at the right time.