The other way around for me.
I used to love playing on a couch with a pad in hand.
Now, i NEED to play with kb/m and sitting on a chair. Any other way and i get hand cramps and back pain.
I can't sit properly on a couch so my back start to hurt like hell in less than an hour. I can alleviate this by lying on my side on the couch but if this position is perfectly fine to watch TV, it is not when you want to play a video game.
And then the gamepad : no matter how ergonomic a pad is, playing with one render my pinkies and ring fingers numb in about half a hour (less if it's not designed to be ergonomic, like most portable consoles for instance) and if i persist, it will start to quickly hurt like hell. And in any case, i'm not very talented with my thumbs either way.
So, i am now "forced" to play on a desktop with mouse and keyboard. But i don't complain. PC master race and all. :p