From bodybuilders to wrestlers, leg training is the most important thing you can do for your body. Since your legs are taxxed pretty much more than your arms every single day, you need to add the intensity to train them to the up most ability. You should be able to do 100 bodyweight squats by the time you are 20 years old in a row, and move onto hindu squats. The Indians got one thing right, and it's their progression with joint health and spinal mobility. Test your hamstring. stretch, and do it over again. Keep training upto 500 in a row. It's a maximum workout for maximum gains. Get to it.