A serious struggle most people experience is that obsessive nature some thoughts seems to overpower you with. An inability to let go of thoughts that feel like they are revolving in circles all day, and some times can last for a long period of time. It is in that resistance that keeps the thoughts glued to the cycle. Letting go of the thought is not just a matter of change the song on the stereo its a matter of acknowledging the thought that is vibrating through your head and assessing its prescience.
People with anxiety disorders(dis-order) spend hours in repetitive thought cycles that they find almost impossible to break from. This dwelling on certain thoughts can put the sufferer in an almost mental jail. What you resist, will persist, and then fear creates in, and anxiety. Sometimes the best solution for this, as pointed out in the video, is to vocally acknowledge it and consistently adjust your focus onto something vastly different. Humour does work as well =)
What have you used to stop ruminating thoughts?