Motivation has to come from some kind of positive influence. In other words, arguing isn’t motivating, harassment isn’t motivating, insults aren’t motivating. It’s the same reason why talking about how ugly and disgusting and stupid looking fat people are has never made somebody suddenly succeed in losing weight. A person will much more successfully be motivated by you giving them support for whatever goals they have, taking interest in them and their life and their perspective, and be enthusiastic to see them make progress. In other words:

Motivating: “I’d really love to see you do well with x, I can really see you doing y, it would be really good for you to do z”

Not motivating: “Why haven’t you done x yet? It’s ridiculous that you have y problem. I’m so tired of you doing z.”