If you are so satisfied at the frame or the design of this type of sunglasses, you may actually want to wear it all the time. But you are not satisfied at the not dark lenses which may not protect the strong light for you on the beach or other places. At this time, you could go to the glasses store and let the workers change the lenses for you with more dark ones.
Oh, you are thinking about a natural way to make your sunglasses lenses darker? Anyway, I should tell you that sunglasses lenses are made up of artificial materials and basically it could not be darkened in a natural way. But they do protect your eyes from those harmful lights such as UV. If you really hate them, you could just get another pair of sunglasses at Walmart online store, where things are amazing in terms of design and price.