How can i improve my fitness and strength ?

I'm 13 fairly fit but could be better. Got no upper body strength and want stronger legs to help improve my footy (AFL) kicking distance.How can i improve my fitness and strength ?You will need to start a work out routine. You are young so I would tell you to consult a Dr. before you begin a work out routine. You can start out with a home work out. Maybe get some 2-5lb weights. I could tell you the exercises to do but you may not know what they are if you are not familiar with weight lifting. I would recommend you get a fitness or health magazine where you can look at pictures of exercises and learned the proper form. Don't life heavy weights at first. It takes time to work up your weight. I am a pro body builder and I have been competing for 4 years. It takes a lot of dedication to achieve the body-form you want. Good luck.How can i improve my fitness and strength ?Can do calisthenics help fitness and strength, progressive barbell exercise is best gain strength and muscularity, maybe you too young however, my cousin Kyojin lift barbells when boy, is quite strong boy, some people claim start barbells too young stunt growth, Cousin Kyojin is only 6'-1", 375-452 lbs. now, maybe if start barbells later he now 7'-0", 550-600 lbs.,what you think?