Masturbation is quite normal. It's like having sex alone. So stop being sad or worried about it. However masturbation should be done when you feel sexually excited and not just for the sake of doing it. Masturbation doesn't cause any harm or reduce your penis size or cause erectile dysfunction. There are no problems associated with masturbation. So stop worrying about it. If you still feel that this information is not adequate go visit a doctor and he'll help you out with proper queries.