Moreover, the grading system in bouldering (a form of rock climbing) helps you gauge the difficulty of a certain climbing route, called a "problem". The exciting feeling of finishing a hard bouldering problem is extra rewarding when you choose a problem more difficult than the grade you usually climb. Right now, I climb around a V5 level, so anything above that can be really hard for me!
When you think of your hobbies, what is it that attracts you to them? I think that having at least one productive hobby, in that it produces something, such as making origami, baking or writing, rather than consuming, such as watching television, listening to music or reading, helps me to feel more in control of my life when I am stressed. That is why a lot of my hobbies center around productive activities in which I am either producing new art, music or better climbing skills. That is what makes me feel good!
This is not to say that consuming hobbies are bad; the best hobbies are the ones you can get excited about. As you reflect on what you do in your free time, it might be fun to think of whether your hobbies focus on consuming something or producing something. Neither is better than the other. What is most important is that it makes you feel good while doing it. If it feels relaxing and fun, then you are probably on the right track!
