No yelling! Lol.
An impact will do it if it's big enough but the old school way is to get a pipe wrench on the yoke and let's it rest on the ground while turn in that direction. I bought a 3 foot long pipe wrench from harbor freight for that...it was like 20 bucks.
You need a box of anti-350 lbs.ft.
By the looks of it you are trying to turn the nut the wrong direction to remove it.
Thanks for the help and the smart ass comments.