There is a great possibility you will engage climbing when hiking, however, climbing itself is an exercise on its own that is worthy of engaging and it can as well be engage in the gym.
Whether gym climbing or the outdoor climbing one thing that is certain is, you will work out your muscles to a very great degree and also your body thereby improving your total well being which includes your body and brain.
However, a successful climbing entails having great strength, ability to endure, having agility and good mental control therefore, you have to imbibe the techniques of rock climbing before engaging as a newbie and if you are a pro in it or whichever, let me hit you with some of the reason why climbing is a good exercise