So you got the hat, the gown, and the paper that proves you know what you know, and you've gone on to live at home for a bit while you work and save money/to grad school where you'll further your knowledge in your field/to a new city with a new job(s) that can pay the rent and keep you fed/to something else productive. You get home one night from doing whatever it is you do and sit down. Then you suddenly realize you've been staring at the television for three hours. Then you remember that you realized this same thing last Tuesday as well. Then you feel the darkness of self awareness creep in as you wonder what you're doing with your life, and what the point of it all is. Easy answer: nothing. There is no point. Stop worrying about it, just do what makes you happy, and engage with that as much as possible.
This realization usually comes about when the things you enjoy doing no longer bring you the satisfaction they once did. This is okay, it just means that your brain is growing to a point where it needs more stimulation than what rewatching all of (favorite childhood TV series) is capable of supplying. Achieving this stimulation is easy, though. The two main ways of doing it are by enhancing what you are already doing, or trying something new.
The first way is simple: take what you're doing, and add something to it. Let's continue to use the show-watching as our example. It's a show that you've always loved or just started watching, either way you find yourself sitting on the couch again. As you're watching the show, try looking at different parts of the screen rather than the focal point of the shot. See what's around in the background. Why is it there? Then move to the words the characters are saying. Do they sound right? What were the stylistic decisions that went into writing this page of dialogue? Continue this until you begin picking up on these extraneous details without trying. You're now thinking about the show that you're watching rather than just eyeballing it. If you continue to escalate this, perhaps comparing it to other work by the writers and directors, suddenly you're cultivating a new skill set in film analysis.
The second way is just as simple: pick a thing you're interested in trying, and then do it. Last year, I picked up miniature war gaming because I had always liked the aesthetics and strategy of the games. Last winter, I took some free online courses from Coursera because I wanted to learn about basic philosophy. Last week, I started writing for Odyssey, because I had gotten lazy in my art and wanted to be held accountable to a schedule. The more new things you try, the more you discover what you like and what you don't, the larger your horizon grows, and the better perspective you have.
"But Tristan," you say, "this sounds like you're trying to get us to learn. You know, that thing you said we've been doing for 17 years. Now is our chance to finally stop and relax." Excellent observation, argumentative scarecrow. I personally believe that a human life should be led in pursuit of greater knowledge and understanding of the world and oneself, but I also preach that to gallivant on into this endeavor indefinitely, without resting to breathe with the grass for a spell is to seek self destruction. So, take a break every now and then, put your feet up, finally finish Breaking Bad, and have some pizza. Just remember to get back on the horse and keep at it. The more you know and the more knowledge you engage with, the more fulfilling everything in life becomes and the less likely you are to have those moments where everything just seems to shrink away.