it depends on how much you weigh and you body type.but 20lbs is an good start for 6 weeks but again it all depends on how big you are.like if you where 240lbs and wanted to lose 20lbs in 6 weeks that might seem kinda crappy for almost 2 months work.but if you have a moderate Weight 20lbs would be just fine because you also have to take into account that you might gain 1 or 2lbs in muscle too.personally i don t believe that there is such a thing as a Fun exercise but the ones you said are actually really good cause they workout multiple muscles.
well they say about 3-5 pounds every 2 weeks is healthy.Fun exercises? haha. well wii fit is pretty fun [:But if you dont have a wii then nevermind[:
take martial arts, there fun and very healthy
20 is good. but don t go below 1200 calories a day.
20 lbs. sounds nice to me.