I know this problem all too well and the best method I've found for myself is to listen to music, while playing exactly what you hear in your head. Once you match up thoughts with music, you can start focusing feeling while your mind is playing background music.
It's a painfully slow process for me, but with practice, you can take the focus off the racy part of your mind and put it more on things you need to focus on. Eventually, you can develop a technique for this refocusing for everyday tasks and you can be less distracted throughout the day. I wish you luck. :)