Lens flare is created when light directly strikes the front element of your lens. We are taught to avoid it as a degradation of the image. Unwanted lens flare gets a bad rap because it decreases the sharpness and contrast of your image as light bounces around your lens. When properly controlled, however, it can be used to set the mood and control your scene. I often utilize the sun by backlighting my subject and allowing light to wrap around the subject and hit my lens.
For this challenge, use lens flare to create a dreamy and romantic mood. Shoot into the sun, or use tools that will create lens flare for you.