Creating new habits from old ones

I was getting ready for work this morning and remembered yesterday's post. I thought about the habit I have of eating ice cream every afternoon and I thought...what if I replace that habit with a healthier one? Instead of simply stopping (or hoping to stop) that habit, I can substitute something else for it.
Now this might sound strange, since my favorite food seems to be ice cream, but another one of my favorite foods is grapefruit! So I grabbed a whole grapefruit from the fridge and headed to work. I'm not adhering to a diet. I am tempted never to consider that practice ever again because my tendency is to make short-term, drastic changes, hold out for a few months, loose tons of weight, and then go back to my old ways.

Instead, I'm thinking I'll simply replace my old habits with new, healthier ones. Now on one of my old diets, it would have been a no-no to eat a whole grapefruit in one sitting, but by my calculations, a whole grapefruit is by far healthier than a pint of ice cream!
I'll let you know how this works. So far it's 10:15 am and I'm not tempted to hit the corner store on lunch break for some sweet lactose gourmet goodness, but we'll see what happens later...