The article is basically about convincing you to be optimistic instead of pessimistic. It describes how optimists usually live fuller and wealthier lives. It also tells you that things like laughing, exercising, and the like will also help you lead a healthier and a more optimistic life.
Obviously the picture would have to be light and bright. My basic idea for this would be shooting the glass from the bottom and have it towering above you. This in my opinion would show the glass as optimistic and powerful as opposed to making it small and insignificant.
Another idea, if possible would be framing the image with 2 glasses, one of which is more full then the other, and having the fuller one seem like it is taller then the glass with less liquid.