How do I build muscle mass and strenght?

I am 14 years old and my parents don't let me weight lift so I need an alternate way of building muscle mass and strenght.
Answer:
why wont they let you lift? because it will make you short? thats an old wives tale. go online and do your research showing the benefits of weight training and present it to your parents. explain your goals of wanting a healthy lifestyle by exercise, etc etc etc.. now to answer your question, you can do body weight exercises. pushups, diamond pushups, pullups, squats, dips, these are exercises you can do without weight and still strengthen your muscles.

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