@marxistvegan I can relate to that. When I was told I was drafted to army service, I ran every damn day and went from a "F" for "FAIL" to highest I could compensate for in a year in gym-class.
Funilly enough, I eventually got placed for Quartermaster-specialization together with the future elite sports-people of the country.
Craaazy. Never sportsed since I was released. :-D