Your boss asks you take on a new project, but you’d really rather pass. That’s because—from where you’re sitting—it seems unnecessary. And you’re busy enough with tasks that actually mean something. Yet, even knowing this, you struggle to just say no.

While a well-meaning friend might tell you to “pick your battles,” that advice is easier to give than it is to apply. You want your manager to have a favorable impression of you, but even more importantly, you want to be on the same page regarding your role. Questioning an assignment isn’t simply about maximizing your time: It’s about clarifying your priorities. That’s why it’s so important to properly select when you’ll pitch in and when you’ll push back.

Here’s a handy little guide, so you’ll know what to do the next time you’re asked to do something that looks like a waste of time:

When You Should Do It

If You’ve Never Done it Before

“You can’t judge it until you’ve tried it” is true for more than that obscure dish at a potluck. Trying new things is how you build your skill set, and it could be that you’ll be particularly adept at (or really enjoy) that seemingly random task. It’s shortsighted to think something that requires basic skills automatically can’t teach you anything new. It could be filling in a gap that’ll help qualify you for other opportunities, or complement the work you’re doing.

Truth talk: Is it possible that it’ll be as worthless as you imagined? Yes. But you can only
turn something down sight unseen so often. Say yes this go-round, and next time, you’ll have a leg to stand on when you suggest your time could be better spent elsewhere.

If It’s Really Important to Your Boss

You know that pet project you’ve been eyeing that’s not 100% in your job description? Well, if you’re known for saying “That’s not my job!”—your manager could respond to your proposal using that same retort. Taking on that extra (kinda dull) project only builds goodwill between you and your boss.

Even if there’s no dream project you’re saving up capital for, being there in a pinch still counts. My grandfather used to say, “Help when it’s needed, not when it’s convenient.” For all that you don’t want every crummy project dumped in your lap because you’re known for saying, “OK, fine,” you do want your team to know that you’re someone they can turn to when they need help—even if the task at hand isn’t glamorous.

If It’s Part of Your Job

Yes, this is worth mentioning, no matter how obvious it may seem. Everyone has aspects of their job they’re less excited about, but it’s unrealistic to think you can ignore them.

While you should be sure to let your manager know that you’re interested in more challenging projects, if you’re in a junior role that’s set up as a “catch all” for grunt work, completing it is part of your job. So, keep an eye out for how you might innovate or additional ways to contribute, but know that paying your dues is one of the steps on the ladder to advancement.

When You Should Push Back

When You Truly Don’t Have the Time

It’s unrealistic to think a manager knows exactly what’s on each and every employee’s plate at a given moment. Even if she’s in the loop as far as the scope of your work and key projects, she can’t read your mind (or in this case, your to-do list). She won’t know that those other “small tasks” have actually taken you three straight days and you don’t have the bandwidth for a new project—unless you tell her.

One of my favorite lines to use in this situation is “Could you help me prioritize my project list?” That way you’re not flat-out telling your boss “no,” rather you’re starting a discussion about the best use of your time.

When You Always Get Stuck With It

You have unique talents and abilities, but how can you make that clear if you spend your days doing the menial tasks only you seem to get assigned?

People can fall into routines, and if your colleagues always pass on boring projects and you always offer to pitch in, the assumption may be that you don’t mind. From there, you become the go-to person for that kind of work.

If this sounds familiar, you definitely want to speak up. Politely decline the next sub-par project that comes your way by mentioning that you’re already committed to working on another assignment. And the next time you check in with your boss, reiterate your desire for a more balanced workload.

When You Think It’s a Seriously Bad Idea

Being a go-to person is about more than saying “yes.” It also entails sharing your insights and saving the team from going down a path you think could be fraught with issues.

If you think that (beyond being annoying) a course of action is a waste of resources or is somehow setting the team up to fail, you should always push back. Keep in mind that questioning if a certain course of action makes sense doesn’t have to be combative. When you ask more about the context or direction of a project—because you want to get it right—you’ll learn more about it and maybe realize it’s not so pointless. Or, maybe you’ll still be against it. (If the latter is true, Muse writer Kat Boogaard has great tips for giving your boss this uncomfortable feedback.)

You want to find the balance—to be seen as helpful and dependable, but to feel comfortable speaking up and managing your workload. Before you grudgingly accept another task you’re pretty sure is unnecessary (or dig your heels in), think through the factors above to decide whether taking a stand is worth it.

Photo of co-workers courtesy of Hero Images/Getty Images.