YOU SAID:

I have to go to gym instead of being laying and playing this

INTO JAPANESE

これを敷いて遊ぶのではなく、ジムに行かなければならない。

BACK INTO ENGLISH

You must go to the gym, not play with it.

INTO JAPANESE

ジムに行って遊んではいけない。

BACK INTO ENGLISH

Don't go to the gym to play.

INTO JAPANESE

ジムに遊びに行くな。

BACK INTO ENGLISH

Don't go to the gym.

INTO JAPANESE

ジムには行かないで

BACK INTO ENGLISH

Don't go to the gym.