I boxed for seven years as a schoolkid and young adult and was undefeated as an amateur, but I couldn't get any sparring partners close to my weight and sparring with MUCH bigger guys all the time was no fun, so I drifted away and took up Karate for around ten years and now I'm an old fart and a highly skilled armchair sportsman.
"I remember the days...", and all that kind of stuff.