Cardio, vigorous is better http://extremelongevity.net/2011/08/31/more-vigorous-exercis...
Resistance training, how much is optimal? https://www.ncbi.nlm.nih.gov/pubmed/16287373
How much total activity? http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjourna...
My take on all this: It seems like you want to be burning at least 1000 calories a week. There have been benefits reported at higher levels but the first 1k calories are guaranteed to get you a large proportion of the benefits. A routine of lifting twice a week and doing rigorous cardio 2-3 days a week puts you comfortably in the 1000-1500 calories burned range.
To the people who are saying that the normal activity of everyday life is adequate, you are fooling yourself because you don't want to have to make changes. It's fine if you want to do that but please don't spread FUD to others who don't know any better. You are hurting them.