I've come to enjoy it more as I've got older. The first time I did it, as a relatively young man, I lasted about two seconds before coming. Now that I'm not so hormonal and the nerve endings in my cock are slowly dying off (as they apparently do after you're about 30), I like the slightly "firmer grip" you get that way. And I also tend to find that women who offer anal are more sexually adventurous. Mind you, I would never even think of doing it with somebody who wasn't really up for it. And I would always use masses of lube and be respectful. If she asked me to stop because it was hurting (it can do sometimes, even for anally-experienced women), I would stop immediately. I might suggest trying a different position. But if that was also a failure, I would not persist.