19 signs you're a functioning adult — even if it doesn't feel like it

• Signs you're a functioning adult include being able to say "no" and practicing self-compassion.
• These skills can be hard to develop, and they're crucial for living in the real world.
• This isn't a definitive list, but if you can recognize even some of these behaviors in your own life, you're off to a good start.

If you're waiting for a certificate from the government that says, "Congratulations: You are officially an adult," we are sorry to tell you that you will be waiting forever.

But fear not: There are plenty of ways to know if you're a real, live adult — beyond the fact that you've stopped growing and found a gray hair on your head. 

We've rounded up 19 non-obvious signs that you're no longer a kid, based on the Quora thread "What are some of the most useful skills to know?" as well as scientific research and expert opinion.

We can't promise we've outlined every sign that you've made the Great Transition, but if you've mastered most of these skills, you definitely deserve that certificate.

SEE ALSO: 10 life skills every young professional should have

You accept feedback gracefully

Remember when your teacher would comment on your report card, "Dan frequently calls out in class," or "Sally has difficulty sharing with classmates," and you'd read it and have the urge to shout back, "DO NOT"?

If you've managed to curb that impulse, good job! Because if you haven't, and you're in a performance review with your boss, you just might get fired.

"For most of us it is hard to hear how we made a mistake or could have done something better,"writes Quora user Pedram Keyani.

"An amazing skill (which you can learn through practice) is to set aside your emotional response in the moment and focus on the information presented to you. Some of it will be valid and some of it invalid but let your brain decide that, not your ego."

Depending on what kind of feedback you're receiving, there are different strategies for responding with a cool head. For example, if your boss points out what she thinks is an error and you're not sure she's correct, you can say, "I hadn't thought of that, and I'm going to look into it right away."

You apologize sincerely

Owning up to your mistakes — without getting defensive — can be a sign of maturity.

The apology you give "needs to be sincere, not qualified, not quantified, and also needs to outline how X will not happen again,"Keyani says.

According to one CEO, there's a six-step strategy for successfully saying you're sorry:

1. Act quickly.

2. Apologize in person.

3. Explain what happened.

4. Show how you are going to avoid the problem in the future.

5. Apologize.

6. Make restitution.

Keyani gives an example of what you might say if you were tardy for an appointment:

I'm sorry I was late for the meeting. It must have been frustrating because you spent a lot of time preparing and got up early. I did a poor job accounting for traffic and didn't give myself enough buffer. That is my bad and I'm going to give myself an extra 10 minutes instead of five moving forward.

You manage your time wisely

There will probably never be a time in your life when you aren't juggling multiple personal and professional priorities. Adulthood is about accepting that, and learning to cope with the burden through prioritization.

Perhaps the most important time-management lesson is that you should stick with one task at a time. Research suggests that multitasking is generally counterproductive because the brain expends energy as it readjusts its focus from one activity to another.

You'd be wise, too, to limit the hours you spend working. Decades ago, Henry Ford discovered that productivity started to decline after employees logged more than 40 hours per week. Other research suggests that, after three weeks, 60-hour workweeks become less productive.