Editor’s note: Joy will be a judge at the Women 2.0 Conference on February 14, evaluating the 10 women-led startups pitching live onstage for PITCH SF Startup Competition!

By Joy Marcus (Partner, DFJ Gotham Ventures)

Recently, my 12 year old daughter suffered her first real crisis of confidence. She did badly on a math test (usually an easy A for her). She found out just as she was going to take another test which affected her score on the subsequent test. Not a great sequence of events.

Her reaction “I’m not smart” killed me.

She is in the 7th grade. While she certainly has had her share of relative triumphs and defeats her reaction until now has universally been “I’m great”. As an accomplished horseback rider (with a room full of ribbons to prove it), she literally will fall off a horse and get right back on.

What is going on?

My biggest fear is that in middle school girls begin to lose their mojo. The boys are finally beginning to catch up academically because they can actually figure out where their backpacks are (I know this I have a boy too). And social cues are difficult. You can’t ask a boy out apparently (more on this another time). Even if the whole asking out process is just a series of texts. All of a sudden, the boys don’t seem so stupid and they hold the social keys. So the girls lose some ground both academically and socially.

Girls, hold on to the confidence that you built in grades 1 through 6. Repeat after me “I’m great” and keep repeating it until you believe it.

You will need this in the halls of middle school, at high school and college parties, at your first pitch meeting with an investor and at all subsequent board meetings.

This post was originally posted at Joy Marcus’s blog. Photo credit: wwworks on Flickr.

joymarcusAbout the guest blogger: Joy Marcus is a Partner at DFJ Gotham. Prior to joining DFJ, Joy was General Manager, US for Dailymotion, from its US launch through its acquisition by Orange (France Telecom) in January 2011. Prior to Dailymotion, Joy was SVP Global Marketing at Time Warner and VP Business Development of Barnes&Noble.com, which she helped take public in 1999. Prior to that, she was VP International Business Development at MTV Networks. Follow her on Twitter at @JoyMarcus.