I'm sure this applies to all of us in one or more ways. How do you qualify?
For me it's swimming. Despite only being 25, I don't know how I used to do it when I was 15 or so.
In Yr10 at the state champs I swam a 29.4 second 50m and still got smoked by a bloke named Thorpe. Now, after not swimming a lap inn 8 years, I am clocking up 20 laps in 30 minutes at about 50 seconds a lap with lengthy "breathers" after every second lap.