Both are correct but it all depends on what you are trying to say and the context you want to use it in. The first can be used as follows. "Well why don't you continue doing something that is good for you?" The Second can be used as follows. "Do you want to continue to do something like this or do you want to do something else?" The Something can also be replaced with an activity such as. "Do you want to continue doing swimming?" or "Do you want to continue to do sport?"