Ich möchte mich an den Strand legen und einfach nichts tune

I have just seen this sentence which means “I want to lie on the beach and simple do nothing”.
When should we add “s” to the end of “nicht”?
 

Simply put, nicht means "not" and nichts means "nothing".

Hallo RexV und sfpugh!

You've got it right, sfpugh!

Note that there's a slight misspelling here, RexV: it's actually tun "to do," and not "tune."

Bis zum nächsten Mal,

Liss