Height gain is caused by growth hormone which occurs up to a certain age. You can be up to 25 years old and you don't have to take any action for that. However, if you are more than 25 years of age, you will not be taller. You can drink milk every day because milk contains a lot of calcium which helps your bones to grow. Get enough sleep. If you have a habit of smoking and drinking, give it up. Stay free from mental worries. You can hang in the ring 3-4 times a day for 5-10 minutes. You will get good results. Also, stand with your back to the wall and try to keep yourself straight parallel to the wall. At the same time, try to touch the walls from the ankles to the head on the back of your body. Do this exercise 8 to 10 times. InshaAllah you will get very good results.