It’s way too hot to go running along the Esplanade, and in this humidity we don’t even want to walk to the air-conditioned gym. But we’re perfectly fine turning on the TV and playing with our new Wii Fit, an exercise game that uses a balance board to help you measure weight and find your center of gravity. The board also calculates your body mass index (scary!). Wii Fit is a yoga class, boot camp, and, when you compare your fitness with other users on the Wii network, a competition. Pick one up at Best Buy (various locations), crank up the A/C, and turn your videogame habit into a better body.