Before heading back to graduate school, my brother worked full-time as a personal fitness and strength trainer. Like many trainers, he started out in an established gym and then struck out on his own once he had established an clientele base. Working on his own, he got almost all of his new business from referrals.
Although one might think that a trainer’s trusted long-term clients would be the source of most new business, it was mostly the newer, less established clients who referred new trainees. The established clients had already referred everyone in their social network that might be interested.
That’s how I learned about the weak ties of strength.