Fitness: Rugby is a game of endurance, but unlike most endurance sports, rugby requires many spurts of top speed sprinting followed by some type of wrestling (i.e. tackling). Going out and jogging for mile after mile will have no positive effect on your ability to play rugby. You must taylor your training to the sport.
Below is a great beginner/short session that will help you improve your rugby fitness and can be done in your backyard, at a field, track or even in the street.
10 min warm up: 10 jumping jacks (repeat three times), followed by 10 seal jacks (handclap in front of you), followed by 10 squats (knees behind toes, sit back), followed by 10 pushups, followed by plank position for 1 minute, then do both side plank positions for 1 minute.
Sprints: These are to be done all at pace with a walk back rest: 10 yards, walk back, 20 yards, walk back, 30 yards, walk back, 40 yards, walk back, 60 yards, walk back, 60 yards, walk back, 40 yards, walk back, 30 yards, walk back, 20 yards walk back, 10 yards.
Rest for 2 minutes.
Mark off 30 yards, mark the center, start at the center and sprint 15 yards to one end, turn and sprint 30 yds to opposite end, turn and sprint to middle. Repeat six times.
Cool down: Jog at slow pace for two minutes.
Good luck!