i learned to play the Euphonium when i was... 9 i think, then quickly picked up the trumpet and trombone. then i learned to play the guitar too, and now I'm quite fluent at playing:
Euphonium
Trumpet
Cornet
Trombone
Bass Trombone
Tuba
French Horn
Guitar
Bass Guitar
Banjo
Mandolin
Ukulele
Xylophone
and all those little instruments in between. I'm hoping that list keeps on growing as life progresses :)