When your mind wanders, don't try to stop it. Rather, become aware of the sky. When mind wanders, don't try to stop it, don't try to bring it to some point, to some concentration - no! Allow it to wander, but don't pay much attention to the wandering - because for or against, you remain concerned with the wandering.
Remember the sky, allow the wandering, and just say, "Okay, it is just a traffic on the road. Many people are moving this way and that. The same traffic is going on in the mind. I am just the sky, not the cloud." Feel it, remember it, and remain in it. Sooner or later you will feel that the clouds are slowing down and there are bigger gaps between the clouds.