Your environment has a major influence on your behavior. A "people environment" you find yourself in is one if key environments you can design, and It has a significant influence on your life trajectory.
You infer what is "normal" and what is "expected" from your peer environment, often in semi-conscious manner
In the spirit of this - you can improve your motivation and general chances of achieving some goal if you were to surround yourself with the people who strive in a similar direction.
Community of practice is a powerful way to learn about something/work on a problem. You get set of people directing their efforts into a similar direction, supporting each other and exchanging ideas.
What kind of relationships count?
spending a lot of time together
You are the average of the five people you spend the most time with
You’re not the average of the FIVE people you surround with. It’s way bigger than that. You’re the average of all the people who surround you. So take a look around and make sure you’re in the right surroundings.
I wonder what's the cause of the friend of a friend impact on your life if it's not mediated through behavior change in your friend ??
I wouldn't find it surprising if the impact of FoF was because it increase the probability for the friend to exhibit a behavior change, and as a consequence of that change you're impacted