Relationships are tricky. There’s no real hard and fast rule for making a relationship last. But according to new research, there’s one essential thing you should be doing regularly if you want a long and happy relationship. After surveying 468 couples, researchers discovered a common factor between the most successful couples: gratitude. Couples who expressed their appreciation for one another on a regular basis had a much higher success rate in their relationship than couples who did not. In fact, gratitude was the main component missing in the surveyed relationships that were failing. This goes to show you, a little thanks really does go a long way.