You must be fit and powerful. You must be able to generate power. Second, you have to have good technique. Rowing is very complex because you are moving dynamically with the boat. You have to be in harmony with everyone else, the boat and the water.
Good technique accounts for at least fifty per cent of being a good rower.
Third, you must be psychologically tough. This is where the pain endurance comes in. A race lasts five and a half minutes. Usually after three minutes you think you're in trouble. After three and a half, you think you are going to die.