To get in shape fast? You should try HIGH-intensity interval training and the intervals should definitely include plyometrics (jumps squats, burpees, etc.).
Exercises that engage multiple muscle groups simultaneously, like plyo movements, with that kind of intensity - THAT will get you fit fast. An example is like that Insanity program; long intervals at a high intensity with smaller rest periods.
Another suggestion would be something that I really like to do outside - hill sprints or sprints period! Those REALLY kick my butt.
But in the end, the higher the intensity, the greater the physiological adaptations. ;)