Not all friendships of course. Some are toxic and need culling (like the weeds we pulled these holidays), but good friendships help us train our brains to process and produce complex information.
According to research out of Durham University, it's the diversity of our friendships that gives our brain the best workout. The interactions with people outside our comfort zones; different to us.
And isn't that the rub? So often we're tribal in how we seek out friendships.
People who look, think, act and were raised like us. We gravitate towards what we know. Same values, same beliefs, similar opinions. We do it not just in real life, but on social media too.
But it turns out the best friendships for us are those which open us up more - the ones with people of different races, backgrounds, educations, ages, opinions and cultures.
According to the research, "when people are exposed to a more diverse group of people, their brains are forced to process complex and unexpected information", which in turn helps us become more creative.
How? Because the more we are forced to process complex information, the more our brain is trained to think outside the square and look beyond the obvious. Which, as the researchers point out, is "precisely the hallmark of creative thinking".
Seeking out diverse friendships is not the only way to engage with complex or unexpected information of course. We can also read books, watch foreign films, or immerse ourselves in the arts.
Researchers found seeing things from a new or different perspective can create feelings of "connectedness and kindness".
If the horrendous events of March 15 and the aftermath in this country taught us anything, by way of example, it's about how educating ourselves on other cultures and beliefs and showing inclusivity can work towards healing many of our ingrained social ills.
So it's a good reminder for our kids as they head into a new term, to embrace new and different, to be unafraid of change, to relish challenges and to seek out stuff outside their comfort zone. New, inclusive and diverse friendships may be a good place to start.