Your hobbies are an integral part of your identity. They regenerate the mind and relax the soul. In a world of constant bombardment of nonsense that garbles the mind and often makes one anxious, hobbies are a necessary bastion.
One thing I've learned over the years is that, no matter how stupid or useless a hobby may seem, it can have practical real-world value beyond simple matters of your own pleasure if used properly. So long as your hobby isn't counting blades of grass or the like, you can use it to build a more powerful identity and to help you advance in life.
Let's take a look at some of my own hobbies for example, even the ones that may seem on their face stupid (and let's be honest, we all probably have one or two that fit under that description).
Hobby: Debating hypothetical 'what-if' matches between characters in fiction (and sometimes historical topics as well).
Value: Aside from the vast network of people I've managed to build up with this hobby (which is never something to be underestimated, even online), the manifestations of it made me better at debating, more witty (because the place can be pretty hostile), and impelled me to learn physics and the mathematics to support it- something which had been a burden to me all my life. I'm therefore a more knowledgeable person and I view the universe differently. Throughout it all I learned how to promote myself better as well, and to run a relatively large wiki, which translates into professional prowess. It also reinforces other hobbies that I have.
Hobby: Studying military history.
Value: This one has been a constant in my life. Aside from it making me vastly more knowledgeable about history in general as well as the things we tend to think about when we hear the words 'military history' in unison, it has also made me a better writer. Put simply, I would never have been able to construct the type of epic novel I'm motivated as hell to complete right now without studying this topic. The history of men in arms also has an inspiring effect on the man reading of their exploits. He desires to better himself and show the bravery that they did- and also to learn the lessons of the past and not repeat the bad behaviors.
Hobby: Video making.
Value: The worth of this hobby should never be underestimated. Starting to make videos consistently in 2009 massively improved my prowess as a man. It doesn't matter what the topic is. I make a wide variety of videos on different topics and have a somewhat successful show with a couple of friends. When you make videos, you force yourself to improve your speaking ability and voice dramatically. You will be totally at ease with public speaking by doing this for a few months. This can of course easily expand into talking in other situations. You'll become a better conversationalist as well, thinking faster on your feet, so to speak. Video format also allows you the benefit of examining your body language, and where necessary, correcting weaknesses in it. Another added benefit that shouldn't be overlooked: skill with video making and editing can easily translate into workplace prowess, making you valuable to employers and also helping you to start and promote your own business. Simply put, I recommend this to everyone, particularly guys that are socially awkward. The many benefits for extremely little cost are too large to ignore.
Hobby: Exercise/working out/lifting.
Value: Far, far, too many to list in a short and condensed paragraph. There's simply no excuse not to.
Value: I just started this one a couple of weeks ago (as an extension of my fictional debating hobby, which serves as the show's niche). Firstly, it's another great way to put media content out there- valuable in any business, especially in today's world. Secondly, I have guests on my show, which gives me an opportunity to improve my conversational skills.
Value: You increase your knowledge of a wide variety of topics and add many skills to your personal arsenal. You'll be a deeper thinker, a better storyteller, and if you're good or dedicated enough, you can easily make money in this fashion as well.
Those are just a few hobbies that I have, but you get the point. Hell, even playing World of Warcraft or some other game (in moderation of course), can be useful, since as far as I'm aware, you'll be talking to people via voice and thus become a better speaker and conversationalist. The bottom line is almost anything can be useful if you think of the right way to use it. So start looking. Keep to your own hobbies and acquire new ones. All of it will make you a better man.