I am on the cusp of 70 years of age. I have never raced. I have never done what most riders would call serious bike training, like what a ranked amateur would do. I used to do high intensity intervals on a semi-regular basis, and I did used to sort of track some ride info. Now it is more a matter of just changing the pace over the course of a ride, with an occasional 15-20 mile, fast paced ride. I rarely do any real sprinting, and only for very short distance. Intensity, I guess, is not an adjective I would use much in describing how I ride these days.