What is the Heart rate that you should maintain during exercise to obtain fitness and health benefits?

It depends on your age. A good rule of thumb is to stay between 60%-85% of your maximum heart rate according to your age. Broad age to maximum heart rate range as follows: 20s - 190 bpm, 30s 190 bpm, 40s-180bpm, 50's-170 bpm, 60s-160bpm, 70s-150bpm.