Oops, it doesn't look like 'gym day' is a national day..

Other days

slime

Slime Day
hannah

Hannah Day
cuddle up

Cuddle Up Day
pick me

Pick Me Day
ruby

Ruby Day
lumpy rug

Lumpy Rug Day
cat girl

Cat Girl Day
stress awareness

Stress Awareness Day
get funky

Get Funky Day
lisp

Lisp Day