Gardening can definitely be thought of as a form of exercise. It has got all the components. It can raise your heart rate and it requires a certain amount of muscle tension to sustain your gardening position and posture. Also it can be very repetitive, so some parts of our body are working a lot harder than others for a prolonged period of time. This is actually a very hard form of exercise and it can be the cause of your back and other joint problems if you do not take care.