When you want to convince your boss of something and you have a million reasons for wanting her to agree with you, take a breath. Your boss does not need to know a million reasons why she should agree with you. She only needs to know the ones that are important for her.

Let’s use an example. If you’re trying to convince your boss that you should work on one assignment over the other, take inventory of your rationale. For you, one project is more interesting, higher profile, and related to what you’ve been doing so far in your role. While the other project is mundane, behind the scenes, and unrelated to your actual job description. The latter also requires you to work with coworkers you can’t stand. 

To convince your boss to delegate the more interesting project to you, use the reasons that she will find most compelling. In this case I would focus on the relevancy that this project has and the related experience you’d bring to it. I would leave out that the other project is boring and that you hate your coworkers. Because even though those are valid reasons for not wanting to work on something—it’s not going to get you anywhere with your boss. It may get you somewhere but nowhere good—she may think you are unable to work with different personalities. If you can avoid going there—do so. She only needs reasons that are important for her to make her decision.