Always ask yourself why this character is having the flashback to this moment in time? Was it a life-changing moment? Is he wounded in battle or has horse thrown him? Is he an old man thinking back to this moment and all that came after it?
Will the plot be affected because of what he's remembering? It should be. Why? Because flashback that is only for the sake of giving information to the reader is lazy writing. A flashback that affects the character in present time, gives him a new view of himself, his life, other people, or what happens next in the story is what makes the flashback more interesting and ties it inextricably to the story.
When we work together, I’ll teach you how to use flashback effectively and how to avoid its overuse.