Philosophy addresses the most important question anyone can ask:
How should I live my life?
Most of philosophy is, or at least is about, some normative area of thought. To say something is normative means that it has to do with shoulds and shouldn'ts, goods and bads, oughts and ought nots, and so on.
Now, why does philosophy teach us how to live our lives? Or really:
Why philosophy alone?
Let's compare the other main way of learning about the world: science. Science is about descriptive truths. It's about how things actually are, not really about how they should be. Yes, scientific discoveries can tell us things about ethics--about good and bad, right and wrong--but scientific observation can't detect normative facts directly. (Goodness and badness don't look like anything in a telescope.) So to learn about shoulds--including how you should live your life--we need philosophy.
This is most obviously true when it comes to moral questions, question about how you should act. Should I break my promise to this person? Should I lie in order to protect someone's feelings?
Must I sacrifice my time and energy to help someone I've never met, or may I avoid making that sacrifice? Is it permissible to order the steak, or should I order the salad instead?
Now, you might think that morality is all just opinions, and so those questions don't have real answers. We can talk about that. But if they do have real answers, then it's pretty important to know those answers, isn't it? So at the very least, we would need philosophy to help us figure out whether the truth is out there, in the first place.
Ethics isn't just about morality. It's also about axiology: What kinds of things are good or bad? This is most relevant to our personal lives when we ask:
What kind of life is a good human life?
We humans have been trying to figure this out for a long time. It's safe to say that living a good human life is what we all really want. As Aristotle pointed out: Why would we choose to do anything at all unless we thought that doing that thing helped us, in the long run, live a good human life? Why would we pursue any goals at all unless those goals helped us attain what we really want, in the end? (And what would we really want, in the end, other than a good life, or true happiness?)
We're back to the question of what's good and what's bad, then. If we want true happiness--if we want to lead the best life we can--then we need to know what's best. What's valuable? What's important? Those are normative questions, so they have normative answers. We try to answer them by using philosophy.
So: Should you take that job? Should you marry that person, or break up with that person? Should you have kids? Should you re-connect with a long-lost relative? Should you give up all your possessions and become a hermit? Should you devote your life to God? (Should you devote your life to video games?) We face these kinds of questions pretty regularly, don't we? These aren't like the merely descriptive questions of what time the movie starts, or where you left your keys. Instead, they're important. They might be the most important.
I mentioned that the good human life seems to have something to do with finding true happiness. Happiness is what everyone wants, right? So you might wonder:
Will philosophy make me happy?
Yes. It won't just make you happy by helping you figure out what a good life, a life of true happiness, really is. It will make you happy in other ways.
We humans have big, complex brains. These brains are pretty good for helping us get around in the world. We can find food. We can avoid predators. We can build houses, cars, bridges, and other useful things. But sometimes, because of these big brains, big questions pop into our heads.
Uh oh. We thought we had things figured out. And then someone like Plato or Descartes or Hume comes along, and we realize we haven't figured out as much as we thought we had. Is there anything beyond the physical universe? How do you know you're not dreaming right now? Can we really trust that the world will keep being consistent and predictable? Is there any reason to believe in God or an afterlife? Are the people around us real? Am I really doing everything I should be doing to improve the world?
Those are some important questions, of course, but they're not just important. Let's admit: They're also a bit disturbing. We might be able to ignore them, but should we? And can we, really, once we start thinking about them a lot?
Once you have a question like those, the only way to answer it is by philosophy. There really are answers out there. They can be complicated. They can be tricky. But they're there, and with some effort, we can understand those answers.
Philosophy also provides you with the tools to think about the world around you differently. Once you start thinking philosophically, you'll find new ways of understand and evaluating your world. You'll find yourself applying philosophical analyses to familiar topics, and viewing those topics in new and exciting ways. I can tell you, from firsthand experience, that that's true.
Indeed, many report that philosophy has helped them psychiatrically, as well.* Many of the issues that philosophers consider can be deep and troubling, and so it helps to see how other philosophers have dealt with these topics.
Given all the benefits to your personal life that philosophy can provide, you might wonder:
How do I get philosophy to benefit me?
One of the best things about philosophy is that you don't need to study it in a university setting in order for it to benefit you. You can get started online. There are some great resources out there to give you some brief introductions, and even some detailed treatments of the issues, by experts. You don't need a laboratory or expensive equipment in order to use philosophy.
But at some point, you should think about taking a course in philosophy. You'll have questions, and those questions will lead to more questions. Philosophers tend to be great teachers as well. And nothing can compare to sharing your ideas with the people around you in a classroom, learning to think "on your feet" and defend your views. It can be a challenging journey, at least at first, and so you might want a guide with you.
Further reading ...