Make an inventory of your personality. They'll probably outlive the motivation of the performer. A gym remains the best bet for improving overall fitness. Not only can a workout at a gym have a competitive component, but a gym also has a sense of community that may not be available through the solitude of home exercise. If a gym is not your idea of fun, it may still be unnecessary to spend the money on an exercise machine.
Gardening is an excellent source of exercise.
You could use tires or sandbags for exercise. Rock-hard abdominals can be yours with only minutes of exertion each day. Now you can rock, rock, rock your way to the abs of your dreams. . .