The most obvious answer would obviously be to be proud of your business, happy about your job, enthusiastic about the future and the challenges and opportunities it brings.
But I bet you there's someone out there who would behave differently. That against all odds after accomplishing something with their business, they pull back to a corner. When they've met a goal, they talk about all the things that went wrong with it. When they've reached a deadline, they beat themselves up over something that happened along the way. When the perfect customer walks in, they're happy to see him walk away and give a sigh of relief.
If this is you, you're not alone. And you're not going crazy.
I'm in there with you.
Talking down your business comes from inside of you. But as much as your business is most probably the fruit of your work, your business is not you and it's weaknesses are not your weaknesses necessarily. And it should never be talked down just because you feel under the weather and you feel you could've done better.
Doing business is always uncertain, and there is always something you could have done better. Sometimes it's easier and much more rewarding to be the one who gets to say "I told you so" when something goes pear shaped. What's good to take a note of though is that when you talk down your own work, your business is the one who suffers, and the reward for yourself (of bashing your own head to the brick wall) will be short-lived.
You are the spokesperson for your business. You are the living, breathing business card that gives out a message to the outside world. If it weren't for you, your business would not exist. This is/was/may be your dream, and the way you handle the outcome might turn your pretty dream sour just because you feel like saying "I told you so" and prefer being on the safe side.
What to do, then, instead of "I-told-you-so"s?
*Next time someone asks you how your business is doing, stop before you answer "oh, the usual", "slow", "damn that accountant and manufacturer" or "you won't believe what this customer just said". Before you say anything, think how courageous you are for having started a business in the first place. Not many people do that. Then think of something nice to say. Your business is your friend and your ally.
*Next time you run out of stock because something has been more popular than before, instead of wallowing in "oh, I'm so low in stock and now there's nothing to offer (see the finger pointing this way?!)" run quick and re-order, bash up a factory, or do whatever it takes to get your stock up-to-date and for the next round, perhaps think of a little thing to make your customers' day even better when they're buying from your stock. Make their day, indulge them. They're coming for your product for a reason, and the barrier they have for returning is much easier to get lowered for good while they're making their next purchase or thinking about it. Make them a thank-you card. Or a little note on how to take better care of your product. Or give them a little discount for the next time they come and visit. Or brew them a cuppa and listen in. The options are plain endless and need not cost a fortune (and they need never be tacky and pushing). Make them lovely and fresh, and make them you. It's the thought that counts.
*Next time your perfect customer walks in the (physical or virtual) front door, don't lurk in the corner. Breathe, and softly try the ground beneath your feet. Listen in, be open to new life, and lean into the adventure.