Swimming, swimming in my swimming-pool 
When days are hot when days are cold, in my swimming pool 
Breast-stroke, side-stroke, fancy diving too. 
Don't you wish you never had anything else to do, but.... 

Actions:

Swimming, swimming: swimming action 
In my swimming pool: trace outline of pool 
Days are hot: wipe hand across forehead 
Days are cold: shiver 
Breast-stroke: do the breaststroke 
Side-stroke: do the sidestroke 
Fancy diving: dive action 

Repeat the song a number of times, leaving out each of the above
lines one at a
time but still doing the actions. The last verse should be all
actions and no singing!