Kikar has a story about how Rav Shach used to have boys from the yeshiva build his sukka with him and often the boys who helped build the sukka would get engaged and married during that same year.

Rav Asher Deitsch, one of the rosh yeshivas of Ponevezh today, seems to have adopted the segula. Every year some boys help him build hsi sukka. Last year, it seems, two brother helped him build the sukka and during the year they both got engaged!

Now, this year, more boys have joined in the building of the sukka, including some of the older bachurim who have not had mazel in finding their zivvug until now, and even some boys from the Mir Yeshiva went to help to take advantage of the segula...

And that is how segulas are born..