Note: Not necessarily you need these words for your meditation. It is just if you find it difficult to concentrate see if this can help you.
As you have made your decision to come to sit here for these 20 mins, please be just sitting here for these 20 mins. You are not doing anything else. You are not going anywhere else. You are right here, sitting here. Nothing else. Stop thinking about what has happened today. Stop worrying about or planning for the future. Cut it off immediately. It is OK to cut off the past and the future. Just be now.
When you sit, please sit like a Buddha, by which, I mean no unnecessary movement. Take the least time to settle down, and then sit still. If you feel itching, it is OK. you don’t have to be bothered by it. If it is very painful, it is OK, because you won’t die. Actually it won’t hurt your body in anyway. So it is OK. Just focus on your practice.
If you drift away with thoughts, it is OK. As soon as you realize it just come back to the present.
Whatever comes, let it come. Whatever goes, let it go. Put everything down.