In honor of Earth Day, Burt’s Bees, the natural personal-care product company, is giving away free smoothies tomorrow in Times Square.

Only catch? You have to blend it yourself by generating enough pedal power from a very special hybrid bike that has a blender attached. (Also ideal for the fitness-focused couple’s wedding registry.)

Considering the going rate for a smoothie these days, I’d be willing to break a sweat for one. And given the effort you exert for the snack, you can call it calorie neutral.

Look for the Burt’s Bees bikes and Earth Day cameras in Times Square, tomorrow, April 22, on Broadway between 42^nd and 43^rd from 11:30am-3pm.