When we think of reasons why people go to the gym we usually think that people do it because they want to look better. This is true and is what gets people to the gym in the first place.
BUT..
After going to the gym for approximately 2 years I can fairly say that it has had a more profound effect on my life and is more than just looking better. Going to the gym may start off as a bit of a chore and it may be difficult for you to enjoy your workouts, after a while though you will begin to enjoy them more as you are getting stronger and more confident in yourself. Personally, I love going to work out and I would describe it as my happy place as I can go the gym and let out any negative emotions that have accumulated over the day and jam to my music.
One of the biggest advantages of going to the gym is that it shapes you into a more confident person, i'm not talking about being egotistical but just confident in yourself, I was never the most confident person as a teenager but going to the gym really helped me love myself more and helped me to become a more positive person which I think is a great thing. I have also found that a lot of people who attend the gym frequently are very friendly and helpful, and won't mind giving you a spot or working in with you between sets if there isn't enough equipment.
Looking from the outside you could see that someone may have grown stronger physically but what might not be as obvious is the mental and emotional strength that is also gained. I would guess that it would come from getting physically stronger first and telling yourself that you can keep going and go even harder and push yourself further than before.
Working out also helps you with goal setting as once you start to see yourself changing you become hungry for more and set goals that will be achieved as long as you stay dedicated and this carry's over to every day life.
There are then the obvious benefits such as looking better and stronger and becoming more healthy and conscious of what you put in your body and how the body functions, especially the muscular system.
I have made some great friends within the gym environment that have become more than just gym friends and I think it is a very positive hobby and a great way to strengthen yourself physically, mentally and emotionally.