Actually, I think meditation coaches would say that when your mind is too busy to let go of a thought completely, then it’s OK to simply acknowledge it, and try not to act on it. For example, if you catch yourself thinking “I wonder how I look sitting here with my eyes closed,” you can acknowledge the thought by saying to yourself “I’m thinking about how I look,” but you don’t need to take out your phone and look at selfies. 🙂
Once I notice that I am wandering, come back to concentrate immediately. No self-judging or beating myself up, as these are also part of the wandering-around. There is no content in concentration, while wandering around is full of thought contents.