Nike+ continues to be an incredible personal case study in the world of Marketing with Meaning. Back in August 2008, I first wrote about my experience with the system, and soon after bragged about receiving a printable award for hitting 100 miles. But last weekend I hit an even bigger milestone: the 500-mile mark.

I continue to be convinced that Nike+ is directly responsible for my physical-fitness turnaround. I am now regularly running at least five days a week and logging 20 miles per week. I have lost about 15 pounds without changing my diet at all. I’m playing full-court basketball without getting winded at all. And I feel less stressed out and am enjoying life more. And it’s all because I have a chip in my shoe that updates my information to a website.

My story of hitting the 500-mile mark is but one interesting example of how Nike+ worked its magic on me. As soon as I hit the 100 level, a message on Nikeplus.com challenged me to get to 500. I saw that less than 50,000 of the million-plus members had achieved this. I longed for the “500″ symbol (above) that would be in my virtual trophy case. So I kept on running. It wasn’t my only motivation to be sure, but it became a small obsession each time I synched up my iPod with a new run.

On Saturday, February 28, I looked at my totals and noticed that I was 8.3 miles away from hitting 500. This is double my usual 4-mile run, but I decided to try to knock it out all at once, figuring it would be a good, challenging way to hit this big goal. Sure enough, I powered through in a little more than an hour, and rushed to get credit on the Nike+ site.

When I logged in with the new data, Nike congratulated me on the accomplishment, allowed me to print my 500-mile certificate, and offered the chance for me to buy a T-shirt to celebrate and brag. I literally did not hesitate to link over to the Nike store and buy a T-shirt for about $30, including shipping. It’s one of the most expensive T-shirts I have ever bought, but it celebrates a “priceless” life experience for me.

Hats off to Nike for challenging consumers such as me to improve their lives, and for being smart enough to find innovative ways to monetize the service further with meaningful products. Now I’m off to run again, with the 1,000-mile level in my sights. I plan on hitting it in mid-August!

(Just for fun, I created the graph below that shows how many Nike+ members have hit each accomplishment level.)