The surest way not to succeed, an old saying tells us, is not to try at all (and science tells us that this is also one of the surest routes to end-of-life regrets). One of the most common reasons people don't try is that they're convinced they'll fail--why make an effort when a negative outcome is already all but assured?

But how good are people at estimating the likelihood of success and failure? When we think it's not even worth giving it a go, are we usually right?

According to a fascinating pair of recent blog posts, the answer to these questions is a resounding no. Science is discovering that many of us are pretty dreadful when it comes to assessing our own abilities in key areas of professional success like creativity and persuasiveness.

Yes, you do have what it takes to be creative.

The first study, highlighted on New York magazine's Science of Us blog, deals with the 99 percent perspiration part of the creative process. Innovation, we're told, is largely about experimentation and determination, not instantaneous inspiration. Which sounds like it might be encouraging--you can't control when a flash of genius will hit, after all--but according to new research, most of us actually are excessively discouraged by the reported hard work of creativity. In short, we underestimate our own ability to persevere and come up with creative solutions.

“People tend to doubt their own ability to stick to the tedious trial-and-error part of creative work, suggests a large new study from Northwestern University, published recently in the Journal of Personality and Social Psychology,” writes Melissa Dahl on Science of Us. “Across seven experiments involving more than 1,200 participants, psychologists Brian J. Lucas and Loran F. Nordgren found that people underestimated how many creative solutions they could come up with in a given amount of time, suggesting, the researchers argue, that in a real-life situation, they might give up too easily.”

You're more persuasive than you think.

But we don't just underestimate our creative problem-solving abilities. We're also pretty lousy at estimating our own persuasiveness, according to another study, covered on Harvard Business Review's Web site. In the piece, researcher and Cornell University professor Vanessa K. Bohns explains the findings of her latest research, which suggest we all have a lot more influence at work than we think.

The study asked participants to first estimate how well they'd do at tasks that required persuasiveness, such as convincing others to donate to charity or fill out a survey, and then had them complete these tasks. Their estimated rate of success was compared to the actual rate.

“It's amazing the opportunities we miss because we doubt our own powers of persuasion. Our bosses make shortsighted decisions, but we don't suggest an alternative, figuring they wouldn't listen anyway. Or we have an idea that would require a group effort, but we don't try to sell our peers on it, figuring it would be too much of an uphill battle,” Bohns writes.

Why? While we can vividly imagine the cost of saying yes to a request, most of us fail to imagine the awkwardness of saying no. Getting an agreement, in other words, is easier than you probably think, though in the complete post Bohns does offer some tips on how to best frame requests.

The takeaway is obvious and energizing: Science suggests that you're not living up to your full potential simply because you don't believe in yourself enough. Next time you hesitate to tackle a problem or make a public pitch for your ideas, just remind yourself of this fact for a free and easy shot of instant courage.