Rather than piercing your lovely steak and letting all the delicious juices escape, a simple way to see how done it is is to check how tender it is to the touch. Trick: compare it against the meaty part of your thumb.
Making an “O” with the thumb and each of the fingers makes the thumb muscle get progressively firmer. Index for rare, middle for medium-rare, ring for medium and pinky for well done.
Unless you’re my mate John, who’s a boxer, in his case everything is overcooked.