Rock climbing increases your arm, back, pectoral, and abdominal muscles better than any work out routine.
When you are determined to complete the challenge before you, the same mind set is applied through real-world settings. For example, challenges in school can be overwhelming. However, after accomplishing a new height, you begin to realize that if you can reach heights such as these you can do anything you set your mind to just by taking the time to do so.
Bouldering is when you don't need to use a harness, rope, or any other safety equipment. In order to better strengthen your arms and forearms, people boulder by climbing side to side on the wall or cliff face.