Ride everyday! Even if you ride two blocks and turn around. Build the habbit of riding, the more you do the farther you can go.
Three mile radius! If you can ride three miles in one direction you can run a ton of errands easily. This is where you help the planet. See if you can push back filling up your gas tank an extra day every week, ie. you fill up ever seven days shoot to make it 8 days then nine and so on. make your short trips on a bike.