Provided there is not some underlying medical condition, it sounds like you're just in very poor shape. A good exercise program should do wonders.
I was in a similar situation way back at the first year of high school about 1960. They had just started the federally-mandated physical fitness test and I fared very poorly indeed.
I undertook a program of running and basic weight lifting and by the time I graduated I was in the top percentile.
Do some research. A basic, whole-body strength training program is pretty easy to set up.
I am pretty sure that you dont drink milk to become stronger you need alot of proteins which includes in milk.dairyproduct.bread.green vegetables etc... plus u should exercise like chin ups pull ups squats... you should get strong in 2 weeks if u just eat alot of protein and doing 50 chin ups. 20 pull ups. 30 squats at least 3 times per week however I recommend you to do it everyday. I hope this helped.
Maybe you just need to exercise more. Listening to music really helps you to forget you're exercising while exercising. If you keep at it, you should be just as or maybe even stronger than your friends. Also, you have to eat healthy. You can't eat junk food then exercise. All you'll do is lose the fat you just ate.
Maybe you don't have enough calcium intake to strengthen your bones. Do some activities that strengthen your arm muscles like jungle gym bars.
Simpley practise
Working out more often.
