If you want to have a healthy and strong muscles, then working out to the gym is the simple answer. If you have spare time, then why not going into the gym is your choice. It will not only help you building your muscles but rather it also keeps you healthy. Though, for some people they think that going into the gym is not practical because its quite expensive.
However, what you should be considering is the benefits when you're on the gym. It helps you to burn out calories and fats, it keeps you healthy. Physically and mentally. Working out to the gym will be much fun if you're with your friends.