Here's a perfect example of why you want to practice in rough conditions. Got to get tough against a defense like this:
Playing on a dirty, slippery floor will only make playing on a clean sticky floor easier. Playing with an old slippery ball will only make playing with a new ball easier. Playing outside in rough conditions will only make playing inside easier. Playing against player who foul the crap out of you will only make playing with referees easier. Don’t complain if you have to play under these conditions, just accept it and play your hardest. Always remember this is good practice for your future. Tighten up!