I think I can relate to his fear of sending out invoices. I had the same fear not with sending invoices but more precisely pricing proposal. I would fear that my prices would be too high, that perhaps I would lose the job because of that. That maybe (deep thoughts) that I wasn't worth the money I was asking for (Thankfully I'm not longer thinking this way).
And every time I would send that pricing proposal only after re-reading it 10 times to make sure I leave enough space so I can back down without looking like a total idiot, I would receive an email accepting the pricing proposal and thus re-enforcing that I wasn't charging too much and that everything was ok.
It's important to understand that through your pricing you are setting the perceived value of your services. If you price them too low, people won't bother taking you because their perception of your value will be low. If your price is too high you might be perceived as too greedy.
The last part of your blog post resonated really well with me as well, as an entrepreneur you need to build an entourage of good people who can support and help you overcome you inner fears but also challenge you when they think you're wrong. You need a winning team.