People who really exercise "for themselves" do mostly aerobics. That kind of exercise is really the best for true health and longevity (though not best for looking good naked).Wilko said:I do those things for myself first and foremost! Sure you do buddy, sure you do.
Ask yourself, if you were the last person on the planet and wanted to live as long and healthy a life as possible (for whatever reason), what type of exercise would you do? Probably some light, high-rep weights to prevent age-related osteoporosis and muscle-wasting, plus some moderate cardio to keep yourself overall in decent shape.
Putting on mass would be meaningless unless you literally had to move heavy objects a lot.