Apparently, the secret to surviving 50 years in the truss business is to begin by selling lumber, and then working your way into it. Heart Truss & Engineering in Lansing, MI, and Littfin Lumber (Truss) Company in Winsted, MN, are both celebrating half a century of success this year, and they share some common characteristics: one, they both hail from Midwestern states; two, their founders all started by selling lumber and building materials; and three, they all resisted the urge to expand beyond their means.