What are people who buy the Wii Fit board and games thinking? Do they really believe this replaces a jog in the park or joining a gym? Wii Fit is the number 1 selling video game in the United States for January with 777,000 Wii Fit systems sold.

Nintendo describes Wii Fit with this: "Wii Fit is a combination of fitness and fun, designed for everyone, young and old. By playing Wii Fit a little every day, you, your friends, and your family can work towards personal goals of better health and fitness." Apparently Nintendo hit the sweet spot of how much (or better how little) fitness a huge part of people are willing to do. Lots of people take New Year's resolutions to exercise. This could also be a reason for the continued Wii Fit sales success from the Holidays.
The Wii Fit is supposed to sell for $89.99, but it is in high demand which drives up the price in many places to over $100. This price is of course very little compared to a gym membership that easily costs the price of a Wii Fit each month.

PC Word just published a new video review of the Wii Fit calling it the virtual gym.
See this report for more Nintendo January 2009 sales numbers.