While reheating a steak is going to give you an edible but lack lustre product compared to the just cooked version, it is sometimes a means to an end.
Reheating larger cuts like Roasts or Low N Slow is often not a bad thing to do, it can make catering a large event easier.
In fact, many restaurants will do this deliberately, particularly for Low N Slow.
The trick is to reheat slowly, so you are not stressing or drying the meat.
The easiest method is in a water bath.
Make sure the beat is tightly vacuum sealed or in a large waterproof bag and completely submerged in hot water. If you have Sour Vide you can do this at a controlled temperature.
You can get quite a good result be reheating the meat in a plastic bag, suspended in a cooler full of hot water.
Try to reheat whole cuts and slice for service once they are warm
If you are reheating slices, it is best to have them in a gravy or jus to keep them moist.