Here's a technique for thought stopping that you might want to try.

Hold something in your hand that has some detail or an interesting shape. Without looking at it at all, explore it with your sense of touch. Really try to discern every detail of the item, and commit it to memory. The aim is to gather as much detail as possible, so that you could do a pretty good drawing of it from memory.

While you keep exploring the object, look at a picture or something with quite a bit of detail. Looking out the window works well. Memorise every detail you can see - again, the aim is to be able to do a pretty good drawing from memory later on.

Now, while you keep doing BOTH of those things, count backwards from 100 in your head.

Your thoughts will be stopped quite quickly, especially if you practice this technique.

Once you've stopped them, it's important to then go and do something that you enjoy, but requires concentration. Examples include reading, crosswords, etc.