Rugby is one of the most physically demanding games in terms of player injuries. Since both Rugby Union and Rugby League have gone professional injuries have increased nearly 50% due to rugby players becoming physically stronger and faster and playing with generally more determination.
It's simple, whatever the referee says, it goes. Avoid getting penalties or getting sent off by learning to rise above poor decisions, and keeping disciplined throughout the game. If you get fouled, pick yourself up and get on with the game, lashing out at your opponent can end with your team playing with fewer men, and you not being popular with your teammates.
I'm personally not good at team sports, as I don't like to lose because of a weak link within the team. What I'm now learning to do, is to find that weak link and rectify it. If it means dropping a team member because there is a stronger player, then accept the coach's / managers choice and simply ask what you need to do to get your place back.
Too many players once dropped have a completely negative attitude. Look upon it as a challenge to prove your coach wrong. Train wiser and smarter than before, show commitment to your team, and even if you don't make the first team, at least you can respect yourself for trying and giving 100 percent.