Stop daydreaming about what you could win
Daydreaming about what you could do with lottery winnings is fun and exciting. But you have no control over whether or not that will happen. With poker, you do have control over whether or not you will win and so daydreaming while you are trying to win is obviously too distracting to do good and instead will do harm.
The first thing I would ask yourself is, do you think of poker like
gambling to win or like earning to win? If all you want to do is gamble, then by all means continue to daydream as it adds to the fun of the experience. However, if you want to earn that money you need to rein in your thoughts a lot better.
When you are at your job, do you spend all day daydreaming about what you can do with your next paycheck? Or are you focused on the work ahead of you? Most people have a job to do and focus on that. If you want to earn money instead of gamble for it, you nee to approach it from that perspective. This is a job and I have to focus on my job now. It's work. it may be work you love doing, but it's still work and needs to be approached in that way.
If that's still not enough to get those thoughts out of your head, then try this. Whenever you have thoughts of what you could win, force yourself to think about what you have won. If you haven't won anything yet then stop yourself and say you can't think about the future you have to live in the present.
If none of that helps, you may have "intrusive thoughts". They may be benign for now, but could actually indicate a mental health issue you may want to seek treatment for. I only say this because I have them myself and they can get worse, or switch to focusing on less pleasant things if gone untreated.