I can’t stop my mind from wandering!
Not only is it impossible to stop the mind from wandering - it's crazy to think you can. A wandering mind means your attention is not on the present. Your attention has strayed from the focus of awareness. Every one of us has a mind that wanders, to some degree. One way to get the mind to wander less and be aware, when it does wander, is through the practice of mindfulness and meditation.
The more you practice meditation, the stronger your concentration and sense of calm will be. Sometimes it’s said that the “wandering thoughts are the weights that train the muscles of the mind”. Every time your mind wanders, in the state of meditation, just bring it back to your focus. It's kind of like doing bicep curls for your brain.
It might help to realize that the only way you can know that your mind is wandering (thinking, fantasies, worries) is when you have to come back into awaren