The heart rate is not beneficial, its the exercising of the heart in general. As you continue to exercise you should find that as the heart becomes fitter, it reacts much faster to the bodies needs. For example, someone unfit after exercise could wait 20 minutes for their heart to slow to a resting rate. Someone fit will only have to wait about half a minute. Its the same when resting and then starting to exercise, a fit persons heart will literally jump into action immediately. As you become fitter, you will also notice how the heart rate is lower to achieve the same exertion.
You say your heart rate was 104 after but 54 before exercise? how long did it take to drop to 70?