Mommy help

Anyone have any experince with an extremly whiny 3 yr old. He whines about everything. And I dont knoe why! We have never gave him anything he wants just because he cries.. if I say no it means no. But here lately when I say no he keeps asking why and crying over it.. I have punished and punished and told him thats not how we get things. I tell him to ask nicely without crying and he can have whatever he is aksing for ( not candy, new toys) but to go outside watch a cartoon, he is hot, he is cold, anything like that comes out in a whine.. its so annoying.