During the past few years, we’ve visited quite a few colleges, preparing last year for our oldest’s decision and now giving our youngest a taste of what’s out there. Speaking as the first in my family to attend college and as someone who didn’t visit the school I attended until it was too late to get into another one, these visits are a strangely numbing process.

There’s excitement, of course, about choosing a new home, and yet confusion and concern about making a mistake selecting the place where many of life’s crucial decisions could be formed, as if it’s possible to make the “right” life decision at 18 anyway.

Surprisingly, if you visit enough four-year colleges, the places start to run together. Public or private, expensive or not, many have or are building state-of-the-art student centers. And competition for students has spawned a surprising number of climbing walls, spin-class rooms, sushi restaurants and big-screen TVs — even many of the least expensive four-year colleges remind me of a cross between a sports bar and a cruise ship.

So after visiting lots of schools and trying, unsuccessfully for the most part, to view each spot through our potential student’s eyes, my wife and I concluded that there’s one thing that ultimately separates one school from another: the tour guide.

That’s right: A decision involving perhaps a hundred thousand dollars in educational “value” can boil down to whether a volunteer student tour guide was funny, entertaining, smart or simply a block-head.

In our travels, the schools judged most deficient were the ones that trotted out the most bored and disinterested tour guides, kids who acted (and sometimes even told us) they were a little too important to be leading a tour.

In fact, one tour guide spent a good portion of a 90-minute tour telling us repeatedly she wished they hadn’t called her in, but she was the only one in town and she wished she was still sleeping off the party from last night … and this was a presumably high-achieving student at one of the country’s most highly rated private schools.

And the schools judged best by our sons? Often, it boiled down to tour guides who were enthusiastic, helpful and engaged. People who cared. People who went out of their way to make kids they’d never see again feel welcome, wanted and important. It wasn’t that they were the best advocates for their schools’ academics; it was that they were the most caring.

As it turns out, that same idea applies to students featured in this month’s cover story. Many of them won’t be attending expensive colleges; in fact, most weren’t even on track to graduate from high school not long ago.

But if you read these stories, you’ll find there’s a “tour guide” of sorts who took an interest in these students, someone who helped guide them from almost certain failure to almost certain success.

Someone — a teacher, a relative, a friend, a volunteer — convinced these students that their lives have value, that their efforts to succeed won’t be in vain, that if they focused their energy on accomplishments instead of bad breaks, they could break a cycle of misfortune and make something out of their lives.

Those of us who have been around awhile know that success in life isn’t as simple as just influencing someone in a positive direction. But for the most part, that’s where success begins. Most of us need a push from time to time, and it doesn’t take an expert to do the deed — it only takes someone who cares.

That’s how these teens found their way in life. And without an enthusiastic tour guide somewhere along the line, many of us wouldn’t be where we are today, either.