Images of Allah in prayer

I was recently given a video where a sheikh says that whoever visualizes an image while reciting IYYAKA NA'BUDU WA IYYYAKA NASTAEEN, then he worships that image that he visualized in his head. I am very much tormented because of this. All kinds of images appear in my mind even when I am just washing dishes. I don't believe in them, and I say that Allah is not like anyone or anything. I am afraid to perform prayer because I am afraid of committing shirk because of these thoughts. What should I do in this situation?