Startup Idea : Connecting People With The Same Goals

Different people may have common goals in a certain period of their lives, but they may not be motivated enough when they are acting alone. For example, I may decide to quit smoking, what if there is a place where others with the similar goal can join me? What if there is a competition among them with a prize which makes them more motivated? The idea can be extended to other issues such as loosing weight, reaching to higher level of skill in chess, studying mathematics, saving money and even start up a business.