My previous business was a much harder slog than the current one (which has never had any significant hardships, though I learned to live very frugally from my previous venture, so I don't need to make much money to avoid hardships or debt).
At one point, about two years in, I had burned through over $40k in savings (I invested in the stock market in 1996, and sold almost all of my holdings in 1999 before the bubble burst) and I was over $30k in credit card debt, and with several bills unpaid for two or more months (let's just say I learned exactly how long it takes for various services, like power, water, etc. to be cut off; and I also spent a little time learning about foreclosure rules; juggling which bills you will pay each month in order to maximize runway is pretty stressful, I recommend against it).
Part of the debt was spent on inventory, and it was paid back quickly (within about 90 days), but it took over a year to pay the rest of it down to zero. I had to add consulting revenue to my startup revenue, which was a distraction, but also a much needed rest from going it alone on the startup.
I don't have anything particularly happy to give you. The startup never really took off, but it did (along with about 50% consulting business mostly in the same field as the startup) become comfortably profitable, bought me a new 350Z, paid the mortgage for five years, and equipped a nice home recording studio. I don't have many desires for objects, but the ones I do want tend to be expensive, so I guess I lived pretty well those last couple of years running the business that got me in so much debt.
Rather than platitudes, I'll give you some advice that I wish I'd known back then:
1. Don't go into debt more than you know you can pay off in a month. It's not worth the stress. If you run out of money, and can't raise it from others, pause the startup, do some consulting or get a real job, and pay for it out of pocket rather than with plastic. Cut expenses mercilessly to avoid debt; part of why I started doing well at the end, and have continued to do well throughout starting the new company is that I have very low expenses. If money doesn't go out, you get more runway, even if money isn't coming in. I sold my car when I moved to the valley, by the way, so my only big expense is now housing.
2. Do not go it alone. It is too stressful. I'm a loner by choice and temperament in almost everything. But, if you have no one to share the startup stress with, you will burn out badly. I have a partner, and now an employee, and I'm finding the burdens much easier to handle.
3. Raise money before you need it, or figure out revenue as early as possible. There are two good ways to build a business and one really bad way. The good ways are: On investor money, or on revenue. The bad way: On personal debt.
4. Understand the costs, and embrace it. Startups cost more than money. They mostly cost time, and the opportunity cost of other jobs you could have had. If the benefits of having your own business don't outweigh those costs, you might consider working for someone else. It usually takes years to get to the point where you make as much working for a startup as you would make working for someone else, and most businesses, even those that do not fail, never make the founders rich.
5. Never be without health insurance. In the US, you simply cannot afford to get really sick or injured without coverage. If you are a young, non-smoking, male, you can get good coverage for under $100/month. I think I pay ~$100, and I'm probably older than you and California has higher health insurance premiums than many places.