Jim Rhon's most used one line quote is:

You are the average of the five people you spend the most time with

In today's reading of The Daily Stoic by Ryan Holiday, he challenges us to ask ourselves about the people we spend our time with.

Are they making me better?

Do they encourage me to push foward and hold me accountable?

Or do they drag me down to their level?

Should I spend more or less time with these folks?

Goethe says:

If I know how you spend your time, then I know what might become of you

With every individual I meet, these questions enable me to evaluate whether I choose to pursue a friendship/relationship with them. It's something that through practice you can begin to do subconsciously. It's these types of choices that really impact the trajectory of your life. Think about it.