Having recently passed through the years that have recently been termed the "quarter life crisis", I've learned many things in my life. Of course, I don't in any way think that there's not much more that I need to learn. I think that the most important of all things I've learned is the importance of people.
I'm a scientist (an engineer really, but engineering is a type of science). As a scientist, I thrive on information, evidence, and data. With minor things in life (for example, whether or not it is currently raining), I may just take the word of somebody who tells me that it's true. Why? There's no real loss to me if they're incorrect, lying, or unclear on location. With bigger things, though, I require proof. This is a hallmark of being a scientist. We don't make decisions based on hearsay and we always question the proof that is given to us. As a result, I'm an atheist in the real sense of the word, not what is has become portrayed as in modern times. Atheist simply means "without god". I am without god. Don't worry about it, it's ok. It doesn't mean that I am a disbeliever, I am simply a non-believer. As a result of this, I know that I cannot place the supposed desires of an unproven entity in the sky above the reality of the known world.
What I know most of in this known world is people. We interact with dozens of people on a daily basis, an each of them impacts our lives. The reality is that we are the sum of all factors that determine who we are. This includes ex girlfriends and ex boyfriends whom you're not on speaking terms with. This includes the well dressed man at the mall who complimented you on your hat. This includes the woman working at Tim Horton's who is somehow cheerful at 6 am. We also impact the people we interact with as well. If I am cranky and in a hurry and don't hold a door open for somebody, it impacts their life. Likewise, when I see a girl who clearly has very low self esteem but is wearing some pretty excellent glasses and I go out of my way to compliment her on her glasses, it impacts her life.
No matter what happens with your work, with your sports, with your video games, with anything else, your friends and family will always be there for you. You may not particularly like some of your family, and you may not see your friends as often as you'd like, but they're there. It's part of the job description. As a thank you, we owe it to our friends, our family, and the random people whom we encounter on a daily basis to try and have as much of a positive impact on their lives as we can. When we die, we leave very little behind but some random objects and the impact that we've had on others.
If you want to start getting a little sentimental, you can look at it this way. I impact the life of a small child when I catch their balloon that was trying to escape and tie it around their wrist. That child, then grows up, and impacts the life of another child. This continues for generations. As a result, we, in a way, can live forever.
It doesn't matter what car you drive, what size house you live in, or what (if any) god or gods you choose to worship. What matters is the relationships that you maintain with the people you encounter. What matters is that you somehow leave every person you meet a little bit better off than when you met them. There is nothing of greater importance.