Just a little something to try at home!
Form a circle with your thumb and fore finger (like the ok gesture).
Ask a friend, relative or passing stranger to try to prise your finger and thumb apart. Really concentrate on not letting them do it.
You may find that they break the circle quite easily. 
Now do the same thing. This time, image that there is a steel ring inside your finger and thumb, forming a comlete circle. No way can anyone break this steel ring, go on laugh at them as they try to pull your finger and thumb apart. 
Let me know how you get on.