Of all the exercises available, I would prefer Yogasanas considering it is also one of the outdoor exercise. They don't really take lots of efforts but the outcome of doing Yoga is really awesome. There are several asanas or postures available in Yoga. Though the practicing methodology differs from one person to another, the outcome can be really impressive after regular practice.
Of all the Yoga Asanas that we have, I would say Surya Namaskar is the best work. Suryanamaskar is basically a combination of multiple asanas all together. The literal meaning of the word Suryanamaskar is praying Lord Surya or the Sun God by doing multiple postures.
Surya Namaskar is an interesting Yoga Asana that helps in covering all aspects of exercise. A bare minimum exercise a person will need every day is fulfilled by doing Surya Namaskar. If this Asana is practiced every day, all body related problems will be sorted easily and a person can stay healthy. This Asana is also very helpful in longevity.