I don’t know about you, but my career has been fraught with moments when I lacked sales confidence. When I first started selling, I’d sometimes sit in my car for half an hour before a presentation. Other times, the sales anxiety I’d feel before a big meeting literally made me sick to my stomach.

Believe it or not, the only thing that enabled me to face my customers with confidence was a silly song that I sang to myself over and over. Sounds pathetic, doesn’t it? But now there’s research that shows I wasn’t crazy!

First, a bit about that tune and what it did for me: It was “I Whistle a Happy Tune” from the musical The King and I. My mom used to sing it all the time and it brings back soothing memories.

Here’s why it worked.

When I sang it, the lyrics and the upbeat melody got me to change my posture so that I “resembled” a confident person, even though I wasn’t. In short, I faked confidence.

Whenever I feel afraid, I hold my head erect. And whistle a happy tune so no one will suspect, I’m afraid.

While shivering in my shoes, I strike a careless pose. And whistle a happy tune, and no one ever knows I’m afraid.

The result of this deception is very strange to tell. For when I fool the people I fear, I fool myself as well!”

Harvard Business Review research shows that changing your posture and assuming “power poses” for 2 or more minutes leads to “greater feelings of power and confidence, with higher levels of the dominance hormone and lower levels of the stress hormone.”

It really works.

When you bring an aura of confidence into a sales meeting, your prospects react to you differently. And, in turn, this positive reaction boosts your confidence even more.

Think about this the next time you go into an important meeting. Change your posture — and everything else will change with it. Go ahead: Fake it ‘til you make it.

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