In school, you made friends based on common interests and personalities, but should you remain friends for life? I think you should always be looking for friends to add to your tribe, who offer different skill sets, have distinct hobbies or qualities that make them unique. 

As I approach 30 years old, I have found myself re-evaluating my friendships and figuring out who makes a positive impact on my life, and who brings nothing to the table. Friendships naturally ebb and flow, however I think we can all pin point that one friend who's selfish and who generally leaves you in a worse mood than you started in.

These are the types of people you need to weed out of your circle, because they're not helping you to grow. It's hard enough finding time for friends, you don't have time to spare.

You too may find that you're now a working adult, there are better ways to choose who we spend your time with. You're tight for time, between post-graduate classes, perhaps starting a family, running your own businesses and trying to make it in the working world.

We're picky about who we date, but as a general rule, not picky enough about who our friends are. As a result, may of us spend weekend after weekend with the same crew, or even giving friends chance after chance simply because we don't want to be without them.

We would do better to find people who challenge us to be a better version of ourselves, who push us, and force us to level up through some friendly competition to be spending time with. When your friends and people who you surround yourself with are successful, you will be more likely to be successful too. They become a motivating factor in your life.

Here's a short guide to choosing friends who make you a better person.

1. Don't ditch all your old friends

Don't get me wrong, your oldest friends have helped to make you who you are. Even if you don't have much in common anymore, it doesn't mean you should cut them loose. Unless being with them is making you revert back to a past self you want to forget, or you stress out about meetings more than you enjoy their company, you may want to keep in touch.

Time is precious, if you've decided that you just don't have anything to discuss except for the past, consider limiting your contact with them during holidays or scheduled reunions.

2. Find friends in your field of work

It's great to have work friends for several reasons-- because you'll naturally have things in common, of course, but also because your friends can be your contacts, references, and sounding boards for future career moves. It's nice to bounce ideas off of people who know where you are coming from and what challenges you are facing in your career.

3. Don't rule out friends who are much older, or much younger

Once you leave high school, your friends will likely have stopped being people of exactly the same age. You'll meet lots of people in your career and work life-- and many of them will be significantly older or younger than you. Don't rule them out as friends just because they are in a different stage of life.

While older friends may become voices of wisdom for you, and possible mentors, young people will keep you from getting too jaded in your work. You may also be able to give back through these young people, in the form of recommendations or career advice.

4. Treat your work friends with respect

Just because you met them through work doesn't mean that you should just use them to get ahead-- at that rate, they won't be friends for long. Get to know these people outside of work if possible. Let a select few see the real you.

Be honest, loyal and forthcoming-- and don't be afraid to show a sense of humor. After all, it's only work, and you can't take it too seriously. That's how friends are made.

I think it's fair to say that we all need some time away from work, family, and our main responsibilities to simply enjoy life. This is actually something that is necessary to our well being, so don't be afraid to make some time for new friends or even yourself. It's worth it.