Fire in the belly or heartburn?

As I'm continuing to mentor a group of high-school freshmen on starting a business (posted here), I find that every week I get some fresh insight on entrepreneurship, the 'real' kind, for those of us who're doing it for a living. After the last meeting my co-mentor and I were bemoaning the fact that we don't see the 'fire in the belly' and hoping that it will be lit as the team gets more involved and sees their ideas taking shape. And then I came home and read the continuing grim economic news - the trouble with tracking multiple sources is that you read the same bad stuff multiple times. There's a surfeit of stories about startups shutting down (the lucky ones get bought at a fraction of their valuation from last year) - and it struck me, there's heartburn just as often as fire in the belly. Heartburn is a stomach-related symptom too, and while they are literally focused on the same anatomical region, metaphorically they imply two very different things.

• Fire in the Belly: When you can't go to sleep because you keep thinking up product designs or marketing strategies
  
• HeartBurn: When you can't go to sleep because you're worried about your product or the market out there

• FB: When you chat up your company with everyone you meet and talk about its great potential
• HB: When you talk about how hard it is to run a company with everyone you meet

• FB: When you meet a great potential employee and say 'I want to recruit you!' (thanks Sean/Harvey)
  
• HB: When you meet a great candidate and say 'I don't have the money to recruit you'

• FB: When you run into a problem, you're impatient to resolve it so you can move ahead
  
• HB: When you find a problem, you put off dealing with it because you think it will reveal more problems
  

• FB: During tough economic times, you think 'there must be a way to thrive'
• HB: When the economy is hurting, you think 'it's going to be hard to survive'

• FB: You read a list like this, and think 'of course, this is what entrepreneurs do'
• HB: You read this and think it's just another unrealistic exhortation to 'think positive'