Your mind will find it hard to focus today due to other thoughts, and you will need to deal with this.
It may be hard to stay focussed today when either random thoughts keep interfering or something in particular is hard to keep out of your mind. If it's something in particular you may have to deal with this first before you can concentrate on anything else, but either way, you should take a break from trying to focus and re-set your mind with some meditation.