Why should anyone stop masturbating? Age has nothing to do with it. If you still enjoy doing it, then do it. If you're no longer up to it, then you won't be able to do it in the first place. Furthermore, if your profile is accurate, you're younger than me & I don't visualise my age forcing me to give up masturbation for a great many years yet.
Why in the world would you want to stop masturbating? I'll be 74 very soon and have cut down quite a bit over the years. I've been down to twice a day for a few years now .... and no stopping point in sight yet! Have fun and play safely!