How to grow your hair back

Last month I was in Japan visiting family traveling parts of Japan. I noticed many people with similar feelings towards there hair loss just by my observation, in how they walk, talk to other people even though I didn’t understand what they were saying. I could feel some feeling from them. “So I thought why is this possible” well we all are human beings that live in this world breath the small air eat food that is grown from this earth. So why do we lose our hair through out time. Some say it is stressful situations or unhappiness etc. Can we change our life’s 
Yes we can!!